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<strong>DESCRIPTIONS</strong> <strong>OF</strong> <strong>MEDICAL</strong> <strong>FUNGI</strong><br />

SECOND EDITION<br />

DAVID ELLIS<br />

STEPHEN DAVIS<br />

HELEN ALEXIOU<br />

ROSEMARY HANDKE<br />

ROBYN BARTLEY<br />

MYCOLOGY UNIT<br />

WOMEN’S AND CHILDREN’S HOSPITAL<br />

SCHOOL <strong>OF</strong> MOLECULAR & BIO<strong>MEDICAL</strong> SCIENCE<br />

UNIVERSITY <strong>OF</strong> ADELAIDE<br />

ADELAIDE<br />

AUSTRALIA<br />

2007<br />

Cover: Cryptococcus neoformans, and montages including Microsporum, Candida,<br />

Schizophyllum, Sordaria, Conidiobolus, Fusarium, Bipolaris, Aspergillus, Curvularia,<br />

Saksenaea, Gliocladium, Trichophyton and Phialophora.


Published by the Authors<br />

Mycology Unit<br />

Women’s and Children’s Hospital<br />

North Adelaide 5006<br />

AUSTRALIA<br />

Direct Phone: (08) 8161 7365<br />

International + 618 8161 7365<br />

Direct Fax: (08) 8161 7589<br />

International + 618 8161 7589<br />

Email: dellis@adelaide.edu.au<br />

www.mycology.adelaide.edu.au<br />

© Copyright 2007<br />

The National Library of Australia Cataloguing-in-Publication entry:<br />

Descriptions of medical fungi.<br />

2nd ed.<br />

Bibliography.<br />

Includes index.<br />

ISBN 9780959851267 (pbk.).<br />

1. Fungi - Indexes. 2. Mycology - Indexes. I. Ellis, David (David H.).<br />

579.5<br />

Printed in Adelaide by<br />

Nexus Print Solutions<br />

153 Holbrooks Road<br />

Underdale, South Australia 2032


The Mycology Unit at the Adelaide Women’s and Children’s Hospital has played a key<br />

role in the provision of the Mycology component of the Microbiology Quality Assurance<br />

Program (QAP) organised by the Royal College of Pathologists of Australasia<br />

since its inception in 1979. The idea to provide all laboratories with a set of description<br />

sheets covering medical fungi evolved in the late 1980s and the first edition of this<br />

book was published in 1992. We now provide an updated edition which includes new<br />

and revised descriptions. We have endeavoured to reconcile current morphological<br />

descriptions with more recent genetic data, however in some cases, especially for the<br />

anthropophilic dermatophytes this is currently not possible.<br />

These descriptions have by necessity been kept brief and many have been based on<br />

previous descriptions by other authors. For further information regarding any of the<br />

mycoses or pathogenic fungi mentioned, the reader is referred to the references cited.<br />

For the precise definitions of the mycological terminology used, the reader is referred<br />

to Ainsworth and Bisby’s Dictionary of the Fungi (Kirk et al. 2001).<br />

For many species, antifungal susceptibility data has also been provided. This has<br />

been derived from both the literature and in-house data from Australian clinical isolates<br />

generated by using the CLSI M27-A2 protocol for yeasts and the CLSI M38-A protocol<br />

for moulds. This composite data is provided as a guide only. MIC 90 s for Aspergillus,<br />

Candida, Cryptococcus and Scedosporium species are provided from large Australian<br />

studies based predominantly on primary isolates. In many cases the clinical relevance<br />

of in vitro antifungal susceptibility results remains difficult to interpret, and expert advice<br />

from a consulting microbiologist or infectious disease specialist may be required.<br />

Risk group (RG) recommendations are based on published data and on current laboratory<br />

safety procedures in accordance with the Australian/New Zealand Standard AS/<br />

NZS 2243.3:2002. Safety in laboratories Part 3: Microbiological aspects and containment<br />

facilities.<br />

David Ellis BSc (Hons), MSc, PhD, FASM, FRCPA (Hon).<br />

Associate Professor<br />

School of Molecular & Biomedical Sciences<br />

University of Adelaide<br />

Head, Mycology Unit<br />

Women’s and Children’s Hospital<br />

North Adelaide, Australia 5006<br />

September, 2007<br />

PREFACE


Absidia corymbifera 1<br />

Acremonium 2<br />

Acrophialophora fusispora 3<br />

Alternaria 4<br />

Aphanoascus fulvescens 5<br />

Apophysomyces elegans 6<br />

Aspergillus 8<br />

Aspergillus flavus 9<br />

Aspergillus fumigatus 10<br />

Aspergillus nidulans 11<br />

Aspergillus niger 12<br />

Aspergillus terreus 13<br />

Aureobasidium pullulans 14<br />

Basidiobolus ranarum 15<br />

Beauveria 16<br />

Bipolaris 17<br />

Blastomyces dermatitidis 19<br />

Candida 20<br />

Candida albicans 23<br />

Candida colliculosa 24<br />

Candida dubliniensis 25<br />

Candida fabianii 26<br />

Candida famata 27<br />

Candida glabrata 28<br />

Candida guilliermondii 29<br />

Candida haemulonii 30<br />

Candida inconspicua 31<br />

Candida kefyr 32<br />

Candida krusei 33<br />

Candida lipolytica 34<br />

Candida lusitaniae 35<br />

Candida norvegensis 36<br />

Candida parapsilosis 37<br />

Candida pelliculosa 38<br />

Candida rugosa 39<br />

Candida tropicalis 40<br />

Chaetomium 41<br />

Chrysosporium tropicum 42<br />

Cladophialophora bantiana 43<br />

Cladophialophora carrionii 44<br />

Cladosporium 45<br />

Coccidioides immitis 46<br />

Colletotrichum 48<br />

Conidiobolus coronatus 49<br />

Cryptococcus 50<br />

Cryptococcus albidus 51<br />

Cryptococcus laurentii 51<br />

Cryptococcus gattii 52<br />

Cryptococcus neoformans 53<br />

CONTENTS<br />

Cunninghamella bertholletiae 55<br />

Curvularia 57<br />

Cylindrocarpon 58<br />

Drechslera 59<br />

Epicoccum purpurascens 60<br />

Epidermophyton floccosum 61<br />

Exophiala dermatitidis 62<br />

Exophiala jeanselmei complex 63<br />

Exophiala spinifera complex 65<br />

Exserohilum 66<br />

Fonsecaea 67<br />

Fusarium 68<br />

Fusarium oxysporum 69<br />

Fusarium solani 70<br />

Geotrichum candidum 71<br />

Geotrichum capitatum 72<br />

Gliocladium 73<br />

Graphium 74<br />

Histoplasma capsulatum 75<br />

Hortaea werneckii 77<br />

Lasiodiplodia theobromae 78<br />

Lecythophora hoffmannii 79<br />

Madurella grisea 80<br />

Madurella mycetomatis 81<br />

Malassezia 82<br />

Malbranchea 83<br />

Microsporum 84<br />

Microsporum audouinii 85<br />

Microsporum canis 86<br />

Microsporum canis var. distortum 88<br />

Microsporum canis var. equinum 89<br />

Microsporum cookei 90<br />

Microsporum ferrugineum 91<br />

Microsporum fulvum 92<br />

Microsporum gallinae 93<br />

Microsporum gypseum 94<br />

Microsporum nanum 95<br />

Microsporum persicolor 96<br />

Mortierella wolfii 97<br />

Mucor 98<br />

Mucor amphibiorum 99<br />

Mucor circinelloides 100<br />

Mucor indicus 100<br />

Mucor ramosissimus 100<br />

Nattrassia mangiferae 101<br />

Ochroconis gallopava 102<br />

Onychocola canadensis 103<br />

Paecilomyces 104<br />

Paecilomyces lilacinus 105


Paecilomyces variotii. 106<br />

Paracoccidioides brasiliensis 107<br />

Penicillium 108<br />

Penicillium marneffei 110<br />

Phaeoacremonium parasiticum 111<br />

Phialophora 112<br />

Phialophora richardsiae 112<br />

Phialophora verrucosa 113<br />

Phoma 114<br />

Pithomyces 115<br />

Prototheca 116<br />

Ramichloridium 117<br />

Ramichloridium schulzeri 117<br />

Rhinocladiella 118<br />

Rhinocladiella atrovirens 118<br />

Rhizomucor 119<br />

Rhizomucor miehei 119<br />

Rhizomucor pusillus 120<br />

Rhizopus 121<br />

Rhizopus azygosporus 122<br />

R. microsporus var. microsporus 122<br />

R. microsporus var. oligosporus 123<br />

R. microsporus var. rhizopodiformis 123<br />

Rhizopus oryzae 124<br />

Rhodotorula 125<br />

Rhodotorula glutinis 126<br />

Rhodotorula mucilaginosa 127<br />

Saccharomyces cerevisiae 128<br />

Saksenaea vasiformis 129<br />

Scedosporium apiospermum 131<br />

Scedosporium aurantiacum 131<br />

Scedosporium prolificans 134<br />

Schizophyllum commune 135<br />

Scopulariopsis 136<br />

Sepedonium 137<br />

Sporothrix schenckii 138<br />

Stemphylium 140<br />

Syncephalastrum 141<br />

Trichoderma 142<br />

Trichophyton 143<br />

Trichophyton ajelloi 144<br />

Trichophyton concentricum 145<br />

Trichophyton equinum 147<br />

Trichophyton erinacei 149<br />

Trichophyton interdigitale 151<br />

T. interdigitale var. nodulare 153<br />

Trichophyton mentagrophytes 154<br />

T. mentag. var. quinckeanum 156<br />

Trichophyton rubrum 158<br />

CONTENTS<br />

Trichophyton rubrum granular type 160<br />

Trichophyton schoenleinii 162<br />

Trichophyton soudanense 163<br />

Trichophyton terrestre 164<br />

Trichophyton tonsurans 165<br />

Trichophyton verrucosum 167<br />

Trichophyton violaceum 169<br />

Trichosporon 170<br />

Trichosporon asahii 171<br />

Trichosporon asteroides 172<br />

Trichosporon cutaneum 172<br />

Trichosporon inkin 172<br />

Trichosporon mucoides 173<br />

Trichosporon ovoides 173<br />

Trichothecium roseum 174<br />

Ulocladium 175<br />

Veronaea botryosa 176<br />

Verticillium 177<br />

Microscopy Stains & Techniques 178<br />

Calcofluor White with 10% KOH 178<br />

KOH with Chlorazol Black 178<br />

India Ink Mounts 178<br />

Lactophenol Cotton Blue (LPCB) 179<br />

Direct Microscopic Preparations 179<br />

Cellotape Flag Preparations 179<br />

Slide Culture Preparations 180<br />

Specialised Culture Media 181<br />

Bird seed agar 181<br />

Bromcresol Purple Milk Agar 181<br />

CDBT media 182<br />

CGB media 182<br />

Cornmeal agar 183<br />

Cornmeal glucose sucrose agar 183<br />

Czapek Dox agar 183<br />

Dixon’s agar 183<br />

Hair perforation test 184<br />

Lactritmel agar 184<br />

Littman oxgall agar 184<br />

Malt extract agar 185<br />

1% Peptone agar 185<br />

Potato dextrose agar 185<br />

Rice grain slopes 185<br />

Sabouraud dextrose agar 186<br />

Sabouraud dextrose agar 5% NaCl 186<br />

Tap water agar 187<br />

Urease agar with 0.5% glucose 187<br />

Vitamin free agar 187<br />

References 188


Descriptions of Medical Fungi<br />

Absidia corymbifera (Cohn) Saccardo & Trotter<br />

The genus Absidia is characterised by a differentiation of the hyphae into arched stolons<br />

bearing more or less verticillate sporangiophores at the raised part of the stolon<br />

(internode), and rhizoids formed at the point of contact with the substrate (at the node).<br />

This feature separates species of Absidia from the genus Rhizopus, where the sporangia<br />

arise from the nodes and are therefore found opposite the rhizoids. The sporangia<br />

are relatively small, globose, pyriform or pear-shaped and are supported by a<br />

characteristic funnel-shaped apophysis. This distinguishes Absidia from the genera<br />

Mucor and Rhizomucor, which have large, globose sporangia without an apophysis.<br />

Absidia currently contains 21 mostly soil-borne species. A. corymbifera is a known<br />

human pathogen causing pulmonary, rhinocerebral, disseminated, CNS or cutaneous<br />

zygomycosis.<br />

Colonies are fast growing, floccose, white at first becoming pale grey with age, and<br />

up to 1.5 cm high. Sporangiophores are hyaline to faintly pigmented, simple or sometimes<br />

branched, arising solitary from the stolons, in groups of three, or in whorls of up<br />

to seven. Rhizoids are very sparingly produced and may be difficult to find without the<br />

aid of a dissecting microscope to examine the colony on the agar surface. Sporangia<br />

are small (10-40 µm in diameter) and are typically pyriform in shape with a characteristic<br />

conical-shaped columella and pronounced apophysis, often with a short projection<br />

at the top. Sporangiospores vary from subglobose to oblong-ellipsoidal (3-7 x 2.5-4.5<br />

µm), hyaline to light grey and smooth-walled. Temperature: optimum 35-37 O C; maximum<br />

45 O C. RG-2 organism.<br />

For descriptions of species, keys to taxa and additional information see Ellis and Hesseltine<br />

(1965 and 1966), Hesseltine and Ellis (1964 and 1966), Nottebrock et al. (1974),<br />

O’Donnell (1979), Samson et al. (1995), Domsch et al. (1980), McGinnis (1980), de<br />

Hoog et al. (2000) and Ellis (2005b).<br />

Key Features: zygomycete, small pyriform-shaped<br />

sporangia with a characteristic conical-shaped columellae<br />

and pronounced apophysis, rapid growth at<br />

40 O C.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.03-2 1<br />

Flucytosine >256 >256<br />

Fluconazole >16 >16<br />

Itraconazole 0.03-2 0.5<br />

Posaconazole 0.03 - 1 0.25<br />

Voriconazole 2->64 >16<br />

Very limited data, antifungal susceptibility testing<br />

of individual strains is recommended. Sun et<br />

al. (2002), Dannaoui et al. (2003), Espinel-Ingroff<br />

et al. (2001), Espinel-Ingroff (2003, 2006), Singh<br />

et al. (2005), Sabatelli et al. (2006) and WCH inhouse<br />

data.<br />

15 µm<br />

1<br />

A. corymbifera showing a typical<br />

pyriform-shaped sporangium<br />

with a conical-shaped columella<br />

and pronounced apophysis (arrow).


2<br />

Descriptions of Medical Fungi<br />

Acremonium Link ex Fries<br />

Colonies are usually slow growing, often compact and moist at first, becoming powdery,<br />

suede-like or floccose with age, and may be white, grey, pink, rose or orange in<br />

colour. Hyphae are fine and hyaline and produce mostly simple awl-shaped erect phialides.<br />

Conidia are usually one-celled (ameroconidia), hyaline or pigmented, globose<br />

to cylindrical, and mostly aggregated in slimy heads at the apex of each phialide.<br />

The genus Acremonium currently contains 100 species, most are saprophytic being<br />

isolated from dead plant material and soil. However a number of species including A.<br />

falciforme, A. kiliense, A. recifei, A. alabamensis, A. roseogriseum and A. strictum are<br />

recognised as opportunistic pathogens of man and animals, causing mycetoma, mycotic<br />

keratitis and onychomycosis. RG-2 for species isolated from humans.<br />

Microconidial Fusarium isolates may be confused with Acremonium, but they usually<br />

grow faster and have colonies with a characteristic fluffy appearance.<br />

Key Features: hyphomycete with solitary, erect, hyaline, awl-shaped phialides producing<br />

single-celled, globose to cylindrical conidia, mostly in slimy heads.<br />

For descriptions of species, keys to taxa and additional information see Gams (1971),<br />

Domsch et al. (1980), Samson et al. (1995) and de Hoog et al. (2000).<br />

10 µm<br />

Acremonium showing long awl-shaped phialides producing cylindrical,<br />

one-celled conidia mostly aggregated in slimy heads at the<br />

apex of each phialide.<br />

Antifungal<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

MIC µg/mL<br />

Range<br />

Itraconazole 0.5->8 Amphotericin B 0.5-16<br />

Posaconazole 0.06-4 Caspofungin 0.03->8<br />

Voriconazole 0.06-4 Anidulafungin 0.5->8<br />

Very limited data, antifungal susceptibility testing of individual strains<br />

is recommended. Guarro et al. (1997), Pfaller et al. (1998, 2002a),<br />

Espinel-Ingroff (2003), Cuenca-Estrella et al. (2006) and WCH inhouse<br />

data.


Descriptions of Medical Fungi 3<br />

Acrophialophora fusispora (S.B. Saksena) Samson<br />

Colonies fast growing, greyish-brown with a black reverse. Conidiophores arising singly,<br />

terminally and laterally from the hyphae, erect, straight or slightly flexuose, tapering<br />

towards the apex, pale brown, rough-walled, up to 15 μm long, 2-5 μm wide, with<br />

whorls of phialides on the upper part. Phialides flask-shaped with a swollen base<br />

and a long, narrow neck, hyaline, smooth-walled or echinulate, 9-15 x 3-4.5 μm in the<br />

broadest part. Conidia in long chains, limoniform, one-celled, pale brown 5-12 x 3-6<br />

μm, smooth to finely echinulate with indistinct spiral bands. Temperature: optimum<br />

40 O C; maximum 50 O C.<br />

The genus Acrophialophora contains 3 species and is most commonly associated with<br />

soil, especially from India. A. fusispora is a rare human pathogen. RG-1 organism.<br />

Key Features: hyphomycete with flask-shaped phialides producing long chains of<br />

one-celled, limoniform, pale brown conidia, with indistinct spiral bands.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), de Hoog et al. (2000) and Al-Mohsen et al. (2000).<br />

10 μm<br />

Culture, phialides and conidia with striations (arrows) of A. fusispora.<br />

Antifungal<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

MIC µg/mL<br />

Range<br />

Fluconazole 8-32 Amphotericin B 0.25-2<br />

Itraconazole 0.06-0.125 Flucytosine >64<br />

Voriconazole 0.06 Posaconazole 0.03<br />

Very limited data, antifungal susceptibility testing of individual strains<br />

is recommended. Al-Mohsen et al. (2000) and WCH in-house data.


4<br />

Descriptions of Medical Fungi<br />

Colonies are fast growing, black to olivaceous-black or greyish, and are suede-like to<br />

floccose. Microscopically, branched acropetal chains (blastocatenate) of multicellular<br />

conidia (dictyoconidia) are produced sympodially from simple, sometimes branched,<br />

short or elongate conidiophores. Conidia are obclavate, obpyriform, sometimes ovoid<br />

or ellipsoidal, often with a short conical or cylindrical beak, pale brown, smooth-walled<br />

or verrucose.<br />

The genus contains 44 species, most are plant parasites, but a few species are ubiquitous<br />

and are also frequently soil-borne. A. alternata is the most common of these.<br />

Although usually seen as saprophytic contaminants, Alternaria species are recognised<br />

causative agents of mycotic keratitis.<br />

Alternaria species soon lose their ability to sporulate in culture. Potato dextrose agar<br />

and cornmeal agar are the most suitable media to use, and incubation under near<br />

ultra-violet light is recommended to maintain sporulation. Temperature: optimum 25-<br />

28 O C; maximum 31-32 O C. RG-1 organism.<br />

Key Features: dematiaceous hyphomycete producing chains of darkly pigmented,<br />

ovoid to obclavate dictyoconidia, often with short conical or cylindrical beaks.<br />

For descriptions of species, keys to taxa and additional information see Simmons (1967),<br />

Ellis (1971), Domsch et al. (1980), Samson et al. (1995), de Hoog et al. (2000).<br />

Antifungal<br />

Alternaria Nees ex Fries<br />

20 μm<br />

Alternaria alternata showing branched acropetal chains and multi-celled,<br />

obclavate to obpyriform conidia with short conical beaks.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

Range MIC90 Fluconazole 16->64 >64 Amphotericin B 0.125->16 2 (4)<br />

Itraconazole 0.125-2 1 Flucytosine >128 >128<br />

Voriconazole 0.5-2 1 Posaconazole 0.06-0.25 0.25<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Pujol et al. (2000), Espinel-Ingroff et al. (2001),<br />

Espinel-Ingroff (2003), Sabatelli et al. (2006) and WCH in-house data.


Descriptions of Medical Fungi 5<br />

Aphanoascus fulvescens (Cooke) Apinis<br />

Colonies are moderately fast growing, white to tan with the production of numerous<br />

spherical, pseudoparenchymatous, buff to light brown cleistothecia (non-ostiolate<br />

ascocarps). Asci are subspherical to ellipsoidal and eight-spored. Ascospores light<br />

brown, yellowish to pale brown in mass, irregularly reticulate, lens-shaped, 3.5-4.7 x<br />

2.5-3.5 µm. Aphanoascus fulvescens has a Chrysosporium anamorph showing typical<br />

pyriform to clavate-shaped conidia with truncated bases, 15.0-17.5 x 3.7-6.0 µm,<br />

which are formed either intercalary, laterally or terminally.<br />

Aphanoascus fulvescens is a soil keratinolytic ascomycete which occasionally causes<br />

dermatomycosis in man and animals. RG-2 organism.<br />

Key Features: keratinolytic ascomycete with a Chrysosporium anamorph.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980) and de Hoog et al. (2000).<br />

100 μm<br />

10 μm<br />

Culture, cleistothecium and conidia of Aphanoascus fulvescens.


6<br />

Descriptions of Medical Fungi<br />

Apophysomyces elegans Misra, Srivastava & Lata<br />

Colonies are fast growing, white, becoming creamy white to buff with age, downy with<br />

no reverse pigment, and are composed of broad, sparsely septate (coenocytic) hyphae<br />

typical of a zygomycetous fungus. Sporangiophores are unbranched, straight or<br />

curved, slightly tapering towards the apex, up to 200 µm long, 3- 5 µm in width near<br />

the apophysis, and hyaline when young but developing a light to dark brown pigmentation<br />

and a conspicuous sub-apical thickening 10-16 µm below the apophysis with age.<br />

Sporangiophores arise at right angles from the aerial hyphae and often have a septate<br />

basal segment resembling the “foot cell” commonly seen in Aspergillus. Rhizoids are<br />

thin-walled, subhyaline and predominantly unbranched. Sporangia are multispored,<br />

small (20-50 µm diameter), typically pyriform in shape, hyaline at first, sepia-coloured<br />

when mature, columellate and strongly apophysate. Columellae are hemispherical in<br />

shape and the apophyses are distinctively funnel or bell-shaped. Sporangiospores are<br />

smooth-walled, mostly oblong, occasionally subglobose, (3-4 x 5-6 µm), subhyaline to<br />

sepia in mass. Good growth at 26 O C, 37 O C and 42 O C. RG-2 organism.<br />

Apophysomyces elegans is readily distinguishable from other zygomycetes of medical<br />

importance, especially the morphologically similar, strongly apophysate pathogen<br />

Absidia corymbifera, by having sporangiophores with distinctive funnel or bell-shaped<br />

apophyses and hemispherical-shaped columellae. In addition, there is a conspicuous<br />

pigmented sub-apical thickening which constricts the lumen of the sporangiophore<br />

below the apophysis, and there are also distinctive foot cells.<br />

Laboratory identification of this fungus may be difficult or delayed because of the<br />

mould’s failure to sporulate on the primary isolation media or on subsequent subculture<br />

onto potato dextrose agar. Sporulation may be stimulated by the use of nutrient<br />

deficient media, like cornmeal-glucose-sucrose-yeast extract agar, Czapek Dox agar,<br />

or by using the agar block method described by Ellis and Ajello (1982) and Ellis and<br />

Kaminski (1985).<br />

Key Features: zygomycete, rare human pathogen usually associated with invasive<br />

lesions following the traumatic implantation of the fungus through the skin. Soil fungus<br />

with a tropical to sub-tropical distribution. Characteristic “cocktail glass” apophysate<br />

sporangial morphology with conspicuous sub-apical thickening of the sporangiophore,<br />

rapid growth at 42 O C.<br />

For descriptions of species, keys to taxa and additional information see Cooter et al.<br />

(1990), Ellis and Ajello, (1982), Misra et al. (1979), Padhye and Ajello (1988), Lawrence<br />

et al. (1986), Wieden et al. (1985), de Hoog et al. (2000) and Ellis (2005b).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range Range<br />

Fluconazole >64 Amphotericin B 0.03-2<br />

Itraconazole 0.03-8 Flucytosine >256<br />

Posaconazole 0.03-4 Voriconazole 8->64<br />

Very limited data, antifungal susceptibility testing of individual strains is<br />

recommended. Sun et al. (2002), Dannaoui et al. (2003), Sabatelli et al.<br />

(2006) and WCH in-house data.


Descriptions of Medical Fungi 7<br />

Apophysomyces elegans Misra, Srivastava & Lata<br />

10 μm 10 μm<br />

a b<br />

(a) Young, multispored, pyriform sporangium of A. elegans showing a typical funnel-shaped<br />

apophysis but without the sub-apical thickening of a more mature<br />

sporangiophore. (b) Mature sporangium of A. elegans showing distinctive funnel-shaped<br />

apophyses, columellae, and a conspicuous pigmented sub-apical<br />

thickening which constricts the lumen of the sporangiophore below the apophysis<br />

(arrow). Sporangiospores are smooth-walled, oblong and subhyaline.


8<br />

Descriptions of Medical Fungi<br />

Aspergillus Micheli ex Link<br />

Colonies are usually fast growing, white, yellow, yellow-brown, brown to black or<br />

shades of green, mostly consisting of a dense felt of erect conidiophores. Conidiophores<br />

terminate in a vesicle covered with either a single palisade-like layer of phialides<br />

(uniseriate) or a layer of subtending cells (metulae) which bear small whorls of<br />

phialides (the so called biseriate structure). The vesicle, phialides, metulae (if present)<br />

and conidia form the conidial head. Conidia are one-celled, smooth or rough walled,<br />

hyaline or pigmented are produced in long dry chains which may be divergent (radiate)<br />

or aggregated in compact columns (columnar). Some species may produce Hülle cells<br />

or sclerotia.<br />

For identification, isolates are usually inoculated at three points on Czapek Dox agar<br />

and 2% malt extract agar and incubated at 25 O C. Most species sporulate within 7<br />

days. Descriptions are primarily based on colony pigmentation and morphology of the<br />

conidial head. Microscopic mounts are best made using cellotape flag or slide culture<br />

preparations mounted in lactophenol cotton blue. A drop of alcohol is usually needed<br />

to remove bubbles and excess conidia.<br />

Key Features: hyaline hyphomycete showing distinctive conidial heads with flaskshaped<br />

phialides arranged in whorls on a vesicle.<br />

For descriptions of species, keys to taxa and additional information see Raper and<br />

Fennell (1965), Domsch et al. (1980), McGinnis (1980), Onions et al. (1981), Samson<br />

and Pitt (1990), Samson et al. (1995), de Hoog et al. (2000) and Klich (2002).<br />

a<br />

conidia<br />

phialides<br />

vesicle<br />

stipe<br />

metulae<br />

Conidial head morphology in Aspergillus (a) uniseriate, (b) biseriate.<br />

b


Descriptions of Medical Fungi 9<br />

On Czapek Dox agar, colonies are granular,<br />

flat, often with radial grooves, yellow<br />

at first but quickly becoming bright to dark<br />

yellow-green with age. Conidial heads<br />

are typically radiate, later splitting to form<br />

loose columns (mostly 300-400 µm in diameter),<br />

biseriate but having some heads<br />

with phialides borne directly on the vesicle<br />

(uniseriate). Conidiophore stipes are<br />

hyaline and coarsely roughened, often<br />

more noticeable near the vesicle. Conidia<br />

are globose to subglobose (3-6 µm in<br />

diameter), pale green and conspicuously<br />

echinulate. Some strains produce brownish<br />

sclerotia.<br />

A. flavus has a world-wide distribution and<br />

normally occurs as a saprophyte in soil<br />

and on many kinds of decaying organic<br />

matter, however, it is also a recognised<br />

pathogen of humans and animals. RG-2<br />

organism.<br />

Key Features: spreading yellow-green<br />

colonies, rough-walled stipes, mature<br />

vesicles bearing phialides over their entire<br />

surface and conspicuously echinulate<br />

conidia.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.06->8 4<br />

Itraconazole 0.03-8 0.5<br />

Voriconazole 0.03-2 0.5<br />

Posaconazole 0.03-1 0.5<br />

Anidulafungin


10<br />

Descriptions of Medical Fungi<br />

On Czapek Dox agar, colonies show typical<br />

blue-green surface pigmentation with<br />

a suede-like surface consisting of a dense<br />

felt of conidiophores. Conidial heads are<br />

typically columnar (up to 400 x 50 µm<br />

but often much shorter and smaller) and<br />

uniseriate. Conidiophore stipes are short,<br />

smooth-walled and have conical-shaped<br />

terminal vesicles which support a single<br />

row of phialides on the upper two thirds<br />

of the vesicle. Conidia are produced in<br />

basipetal succession forming long chains<br />

and are globose to subglobose (2.5-3.0<br />

µm in diameter), green and rough-walled<br />

to echinulate. Note: This species is thermotolerant<br />

and grows at temperatures up<br />

to 55 O C.<br />

A. fumigatus is truly a cosmopolitan mould<br />

and has been found almost everywhere<br />

on every conceivable type of substrate. It<br />

is an important pathogen of humans and<br />

animals. RG-2 organism.<br />

Key Features: uniseriate and columnar<br />

conidial heads with the phialides limited<br />

to the upper two thirds of the vesicle and<br />

curving to be roughly parallel to each<br />

other.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.03->8 2<br />

Itraconazole 16 0.5<br />

Voriconazole


Descriptions of Medical Fungi 11<br />

Aspergillus nidulans (Eidam) Wint.<br />

Teleomorph: Emericella nidulans (Eidam) Vuill.<br />

On Czapek Dox agar, colonies are typically plain green in colour with dark red-brown<br />

cleistothecia developing within and upon the conidial layer. Reverse may be olive to<br />

drab-grey or purple-brown. Conidial heads are short columnar (up to 70 x 30 µm in<br />

diameter) and biseriate. Conidiophore stipes are usually short, brownish and smoothwalled.<br />

Conidia are globose (3-3.5 µm in diameter) and rough-walled.<br />

A. nidulans is a typical soil fungus with a world-wide distribution, it has also been reported<br />

causing disease in human and animals. RG-1 organism.<br />

Key Features: conidial heads are short columnar and biseriate. Stipes are usually<br />

short, brownish and smooth-walled. Conidia are globose and rough-walled.<br />

20 μm<br />

10 μm 20 μm<br />

a b c<br />

(a) Cleistothecium of Emericella nidulans (anamorph Aspergillus nidulans) showing<br />

numerous reddish-brown ascospores and thick-walled hülle cells; (b) cleistothecia are<br />

often surrounded by a mass of hülle cells which are up to 25 µm in diameter; (c) conidial<br />

head and stipe and (d) culture of A. nidulans.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.125-4 2<br />

Itraconazole 0.03-8 0.25<br />

Voriconazole 0.125-4 0.25<br />

Posaconazole 0.03-1 0.25<br />

Caspofungin 0.125-8 nd<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff<br />

(2003), Cuenca-Estrella et al. (2006).<br />

MIC s from Australian clinical isolates (nd<br />

90<br />

= not done).<br />

d


12<br />

Descriptions of Medical Fungi<br />

On Czapek Dox agar, colonies consist of<br />

a compact white or yellow basal felt covered<br />

by a dense layer of dark-brown to<br />

black conidial heads. Conidial heads are<br />

large (up to 3 mm by 15 to 20 µm in diameter),<br />

globose, dark brown, becoming<br />

radiate and tending to split into several<br />

loose columns with age. Conidiophore<br />

stipes are smooth-walled, hyaline or turning<br />

dark towards the vesicle. Conidial<br />

heads are biseriate with the phialides<br />

borne on brown, often septate metulae.<br />

Conidia are globose to subglobose (3.5-5<br />

µm in diameter), dark brown to black and<br />

rough-walled.<br />

A. niger is one of the most common and<br />

easily identifiable species of the genus<br />

Aspergillus, with its white to yellow mat<br />

later bearing black conidia. This species<br />

is very commonly found in aspergillomas<br />

and is the most frequently encountered<br />

agent of otomycosis. It is also a common<br />

laboratory contaminant. RG-1 organism.<br />

Key Features: conidial heads are dark<br />

brown to black, radiate and biseriate with<br />

metulae twice as long as the phialides.<br />

Conidia brown and rough-walled.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.125-2 2<br />

Itraconazole 0.03->8 0.5<br />

Voriconazole


Descriptions of Medical Fungi 13<br />

On Czapek Dox agar, colonies are typically<br />

suede-like and cinnamon-buff to<br />

sand brown in colour with a yellow to deep<br />

dirty brown reverse. Conidial heads are<br />

compact, columnar (up to 500 x 30-50 µm<br />

in diameter) and biseriate. Conidiophore<br />

stipes are hyaline and smooth-walled.<br />

Conidia are globose to ellipsoidal (1.5-2.5<br />

µm in diameter), hyaline to slightly yellow<br />

and smooth-walled.<br />

A. terreus occurs commonly in soil and is<br />

occasionally reported as a pathogen of<br />

humans and animals. RG-2 organism.<br />

Key Features: cinnamon-brown cultures,<br />

conidial heads biseriate with metulae as<br />

long as the phialides.<br />

For descriptions of species, keys to taxa<br />

and additional information see Raper and<br />

Fennell (1965), Domsch et al. (1980),<br />

McGinnis (1980), Onions et al. (1981),<br />

Samson and Pitt (1990), Samson et al.<br />

(1995), de Hoog et al. (2000) and Klich<br />

(2002).<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.06-16 4<br />

Itraconazole 0.03-1 0.25<br />

Voriconazole 0.06-2 0.25<br />

Posaconazole 0.03-2 0.125<br />

Anidulafungin 0.03 nd<br />

Caspofungin 0.015-0.5 nd<br />

Espinel-Ingroff et al. (2001), Pfaller et<br />

al. (2002), Diekema et al. (2003), Espinel-Ingroff<br />

(2003), Serrano et al. (2003),<br />

Cuenca-Estrella et al. (2006). MIC s 90<br />

from Australian clinical isolates (nd = not<br />

done).<br />

Aspergillus terreus Thom<br />

10 μm<br />

Culture and conidial head and conidiophore<br />

of A. terreus. Note: conidial heads<br />

are biseriate.


14<br />

Descriptions of Medical Fungi<br />

Aureobasidium pullulans (de Bary) Arnaud<br />

Colonies are fast growing, smooth, soon covered with slimy masses of conidia, cream<br />

or pink to brown or black. Hyphae hyaline and septate, frequently becoming darkbrown<br />

with age and forming chains of one- to two-celled, thick-walled, darkly pigmented<br />

arthroconidia. These arthroconidia actually represent the Scytalidium anamorph of<br />

Aureobasidium and are only of secondary importance in recognising members of this<br />

genus. Conidia are produced synchronously in dense groups from indistinct scars or<br />

from short denticles on undifferentiated, hyaline to sub-hyaline hyphae. Conidia are<br />

hyaline, smooth-walled, single-celled, ellipsoidal but of very variable shape and size<br />

(8-12 x 4-6 µm), often with an indistinct hilum (= a mark or scar at the point of attachment).<br />

Temperature: optimum 25 O C; maximum 35-37 O C.<br />

This species has two varieties: A. pullulans var. pullulans, with a colony which remains<br />

pink, light brown, or yellow for at least three weeks, and A. pullulans var. melanogenum<br />

which soon becomes black or greenish-black due to dark hyphae which often fall apart<br />

into separate cells. A. pullulans has a world-wide distribution and is usually isolated<br />

as a saprophyte, occasionally from skin and nails. However, it has also been reported<br />

as a rare causative agent of phaeohyphomycosis, mycotic keratitis and peritonitis in<br />

patients on continuous ambulatory peritoneal dialysis (CAPD). RG-1 organism.<br />

Key Features: hyphomycete (so called black yeast) producing hyaline blastoconidia<br />

simultaneously from the vegetative hyphae, which may also form chains of darkly pigmented,<br />

thick-walled arthroconidia.<br />

For descriptions of species, keys to taxa and additional information see Hermanides-<br />

Nijhof (1977), Domsch et al. (1980), McGinnis (1980) and de Hoog et al. 2000.<br />

20 μm<br />

A. pullulans showing chains of one- to two-celled, darkly pigmented arthroconidia of<br />

the Scytalidium anamorph of Aureobasidium and the presence of numerous hyaline,<br />

single-celled, ovoid-shaped conidia which are produced on short denticles.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-2 Itraconazole 0.03-0.25 Voriconazole 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001) and WCH in-house data.


Descriptions of Medical Fungi 15<br />

Synonyms: Basidiobolus meristosporus Drechsler; Basidiobolus heterosporus Srinivasan<br />

& Thirumalachar; Basidiobolus haptosporus Drechsler.<br />

Colonies are moderately fast growing at 30 O C, flat, yellowish-grey to creamy-grey, glabrous,<br />

becoming radially folded and covered by a fine, powdery, white surface mycelium.<br />

Note: satellite colonies are often formed by germinating conidia ejected from<br />

the primary colony. Microscopic examination usually shows the presence of large<br />

vegetative hyphae (8-20 µm in diameter) forming numerous round (20-50 µm in diameter),<br />

smooth, thick-walled zygospores that have two closely appressed beak-like<br />

appendages. The production of “beaked” zygospores is diagnostic for the genus. Two<br />

types of asexual conidia are formed, although isolates often lose their sporulating ability<br />

with subculture and special media incorporating glucosamine hydrochloride and<br />

casein hydrolsate may be needed to stimulate sporulation (Shipton and Zahari, 1987).<br />

Primary conidia are globose, one-celled, solitary and are forcibly discharged from a<br />

sporophore. The sporophore has a distinct swollen area just below the conidium that<br />

actively participates in the discharge of the conidium. Secondary (replicative) conidia<br />

are clavate, one-celled and are passively released from a sporophore. These sporophores<br />

are not swollen at their bases. The apex of the passively released spore has<br />

a knob-like adhesive tip. These spores may function as sporangia, producing several<br />

sporangiospores. RG-2 organism.<br />

Basidiobolus ranarum is commonly present in decaying fruit and vegetable matter, and<br />

as a commensal in the intestinal tract of frogs, toads and lizards. It has been reported<br />

from tropical Africa, India, Indonesia and South East Asia including Australia.<br />

For descriptions of species, keys to taxa and additional information see Strinivasan and<br />

Thirumalachar (1965), Greer and Friedman (1966), Dworzack et al. (1978), McGinnis<br />

(1980), King (1983), Rippon (1988), Davis et al. (1994), Jong and Dugan (2003), de<br />

Hoog et al. (2000) and Ellis (2005a).<br />

20 μm<br />

Basidiobolus ranarum Eidem<br />

a 20 μm<br />

b<br />

(a) Sporophore and conidia and (b) zygospores of Basidiobolus ranarum.


16<br />

Descriptions of Medical Fungi<br />

Colonies are usually slow growing, mostly not exceeding 2 cm in ten days at 20 O C,<br />

downy, at first white but later often becoming yellow to pinkish. The genus Beauveria<br />

is characterised by the sympodial development of single-celled conidia (ameroconidia)<br />

on a geniculate or zig-zag rachis. Conidiogenous cells are flask-shaped, rachiform,<br />

proliferating sympodially and are often aggregated into sporodochia or synnemata.<br />

Conidia are hyaline and globose or ovoid in shape. RG-1 organism.<br />

Three species are recognised, two of which are well known parasites of insects. B.<br />

bassiana is the most common species and is best known as the causal agent of the<br />

disastrous muscardine in silkworms. Beauveria species are occasionally isolated in<br />

the clinical laboratory as saprophytic contaminants.<br />

Key Features: hyphomycete showing sympodial development of ameroconidia on a<br />

geniculate or zig-zag rachis emanating from a flask-shaped conidiophore.<br />

For descriptions of species, keys to taxa and additional information see de Hoog (1972),<br />

Domsch et al. (1980), McGinnis (1980) and de Hoog et al. (2000).<br />

20 μm<br />

Beauveria Vuillemin<br />

Beauveria bassiana showing sympodial development of conidia on a geniculate<br />

or zig-zag rachis. Conidiogenous cells are flask-shaped, rachiform,<br />

proliferating sympodially and are often aggregated into sporodochia or synnemata.<br />

Conidia are hyaline and globose or ovoid in shape, 2-3 mm diameter<br />

(phase contrast image).


Descriptions of Medical Fungi 17<br />

Teleomorph: Cochliobolus Drechsler<br />

Bipolaris Shoemaker<br />

Colonies are moderately fast growing, effuse, grey to blackish brown, suede-like to<br />

floccose with a black reverse. Microscopic morphology shows sympodial development<br />

of pale brown pigmented, pseudoseptate conidia on a geniculate or zig-zag rachis.<br />

Conidia are produced through pores in the conidiophore wall (poroconidia) and are<br />

straight, fusiform to ellipsoidal, rounded at both ends, smooth to finely roughened, germinating<br />

only from the ends (bipolar).<br />

The genus Bipolaris contains about 45 species which are mostly subtropical and tropical<br />

plant parasites; however several species, notably B. australiensis, B. hawaiiensis<br />

and B. spicifera are well documented human pathogens. RG-1 organisms.<br />

Key Features: dematiaceous hyphomycete producing sympodial, pseudoseptate, pale<br />

brown, straight, fusiform to ellipsoidal poroconidia, which are rounded at both ends.<br />

The genera Drechslera, Bipolaris, Curvularia and Exserohilum are all closely related<br />

and differentiation of the genera relies upon a combination of characters including conidial<br />

shape, the presence or absence of a protruding hilum, the contour of the basal<br />

portion of the conidium and its hilum, the point at which the germ tube originates from<br />

the basal cell and, to a lesser degree, the sequence and location of the first three conidial<br />

septa. The table below is modified from Domsch et al. (1980).<br />

Anamorph Main characters Teleomorph<br />

Drechslera Conidia cylindrical, germinating from any cell,<br />

hilum not protuberant<br />

Bipolaris Conidia fusiform-ellipsoidal, central cells not<br />

much darker and broader than the distal ones,<br />

hilum not protuberant, germination bipolar.<br />

Curvularia Conidia with 2-3 broader and darker central<br />

cells, often curved, with or without a prominent<br />

hilum, germination bipolar.<br />

Exserohilum Conidia fusiform-cylindrical to obclavate, with<br />

a protuberant hilum germination bipolar.<br />

Pyrenophora<br />

Cochliobolus<br />

Cochliobolus<br />

Setosphaeria<br />

Species of Bipolaris, Curvularia and Exserohilum are causative agents of phaeohyphomycosis<br />

which is an emerging mycotic infection of humans and lower animals<br />

caused by a number of dematiaceous (brown-pigmented) fungi where the tissue morphology<br />

of the causative organism is mycelial. This separates it from other clinical<br />

types of disease involving brown-pigmented fungi where the tissue morphology of the<br />

organism is a grain (mycotic mycetoma) or sclerotic body (chromoblastomycosis).<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971<br />

and 1976), Luttrell (1978), Domsch et al. (1980), Alcorn (1983), Padhye et al. (1986),<br />

McGinnis et al. (1986b), Sivanesan (1987), Rippon (1988) and de Hoog et al. (2000).<br />

Also see Descriptions for Curvularia, Drechslera and Exserohilum.


18<br />

Descriptions of Medical Fungi<br />

10 μm<br />

Bipolaris australiensis showing sympodial development of pale<br />

brown, fusiform to ellipsoidal, pseudoseptate, poroconidia on a<br />

geniculate or zig-zag rachis.<br />

Antifungal<br />

Bipolaris Shoemaker<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

Range<br />

Itraconazole 0.03-1 Amphotericin B 0.06-2<br />

Posaconazole 0.06-0.05 Anidulafungin 1-4<br />

Voriconazole 0.06-0.05 Caspofungin 1-4<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Pfaller et al. (2002a), Espinel-Ingroff<br />

(2003), McGinnis and Pasarell (1998) and WCH in-house data.


Descriptions of Medical Fungi 19<br />

Blastomyces dermatitidis Gilchrist & Stokes<br />

Colonies (SDA) at 25 O C are variable in morphology and rate of growth. They may grow<br />

rapidly, producing a fluffy white mycelium or slowly as glabrous, tan, nonsporulating<br />

colonies (Fig. a). Growth and sporulation may be enhanced by yeast extract. Most<br />

strains become pleomorphic with age. Microscopically, hyaline, ovoid to pyriform, onecelled,<br />

smooth-walled conidia (2-10 µm in diameter) of the Chrysosporium type, are<br />

borne on short lateral or terminal hyphal branches.<br />

Colonies on blood agar at 37 O C are wrinkled and folded, glabrous and yeast-like. Microscopically,<br />

the organism produces the characteristic yeast phase as seen in tissue<br />

pathology; ie. B. dermatitidis is a dimorphic fungus.<br />

WARNING: RG-3 organism. Cultures of Blastomyces dermatitidis may represent a<br />

biohazard to laboratory personnel and should be handled in an appropriate pathogen<br />

handling cabinet. In the past, conversion from the mould form to the yeast form was<br />

necessary to positively identify this dimorphic pathogen from species of Chrysosporium<br />

or Sepedonium; however, culture identification by exoantigen test is now the method<br />

of choice.<br />

Histopathology: Tissue sections show large, broad-based, unipolar budding yeastlike<br />

cells, which may vary in size from 8-15 µm (Fig. b), with some larger forms up to<br />

30 µm in diameter. Note: tissue sections need to be stained by Grocott’s methenamine<br />

silver method to clearly see the yeast-like cells, which are often difficult to observe in<br />

H&E preparations.<br />

Key Features: clinical history, tissue pathology, culture identification by positive<br />

exoantigen test.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Chandler et al. (1980), Kaufman and Standard (1987) and Rippon (1988).<br />

Antifungal<br />

a b<br />

10 μm<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range MIC Range MIC 90 90<br />

Fluconazole 0.125-64 4-16 Amphotericin B 0.03-1 0.5<br />

Itraconazole 0.03->16 0.125-2 Voriconazole 0.03-16 0.25<br />

Posaconazole 0.03-2 0.125 Caspofungin 0.5-8 2<br />

Limited data available. Sugar and Liu (1996), Espinel-Ingroff et al. (2001),<br />

Espinel-Ingroff (2003), Gonzales et al. (2005) and Sabatelli et al. (2006).


20<br />

Descriptions of Medical Fungi<br />

The genus Candida is characterised by globose to elongate yeast-like cells or blastoconidia<br />

that reproduce by multilateral budding, polar budding if present on a narrow<br />

base, pseudohyphae and occasionally true hyphae may also be present. Arthroconidia,<br />

ballistoconidia and colony pigmentation are always absent. Fermentation or<br />

not: Nitrate assimilation or not: Inositol assimilation or not, however all inositol positive<br />

strains form pseudohyphae. In the past, the genus Torulopsis was separated from<br />

the genus Candida by the absence of pseudomycelium. However, in 1978 Yarrow &<br />

Meyer amended the description of Candida to include all species previously included<br />

in Torulopsis.<br />

Several species of Candida may be aetiological agents, most commonly C. albicans,<br />

followed by C. parapsilosis, C. glabrata, C. krusei and C. tropicalis. However a number<br />

of other species may also be isolated (see table below). All are ubiquitous and occur<br />

naturally on humans.<br />

Identification:<br />

Candida Berkhout<br />

Ensure that you start with a fresh growing pure culture; streak for single colony isolation<br />

if necessary.<br />

Chromogenic agars are now being used for primary isolation for both the detection of<br />

mixed flora and rapid species identification, especially from non-sterile sites.<br />

Germ Tube Test. A rapid screening test for Candida albicans and Candida dubliniensis.<br />

0.5 mL of serum, containing 0.5% glucose, is lightly inoculated with the test organism<br />

and incubated at 35 O C for 2-3 hours. On microscopy, the production of germ tubes by<br />

the cells is diagnostic for Candida albicans.<br />

10 μm<br />

Production of germ tubes by C. albicans.<br />

Species distribution from 944 patients<br />

with candidemia (Australian<br />

Candidemia Study 2002-2004).<br />

Species No %<br />

C. albicans 447 47.3<br />

C. parapsilosis 182 19.3<br />

C. glabrata 167 17.8<br />

C. krusei 46 4.9<br />

C. tropicalis 46 4.9<br />

C. dubliniensis 22 2.3<br />

C. guilliermondii 11 1.2<br />

C. lusitaniae 8 0.8<br />

C. kefyr 5 0.5<br />

C. pelliculosa 3 0.3<br />

C. rugosa 2 0.2<br />

C. colliculosa 1 0.1<br />

C. famata 1 0.1<br />

C. inconspicua 1 0.1<br />

C. lipolytica 1 0.1<br />

C. fabianii 1 0.1


Descriptions of Medical Fungi 21<br />

Candida Berkhout<br />

For the full identification of germ tube negative yeasts, morphological (Dalmau<br />

plate culture), physiological and biochemical tests are essential.<br />

(a) Dalmau Plate Culture: To set up a yeast morphology plate, dip a flamed sterilised<br />

straight wire into a culture to make a light inoculum and then lightly scratch the wire<br />

into the surface of a cornmeal/tween 80, rice/tween 80 or yeast morphology agar plate,<br />

then place a flamed coverslip onto the agar surface covering the scratches. Dalmau<br />

morphology plates are examined in-situ directly under the lower power of a microscope<br />

for the presence of pseudohyphae which may take up to 4-5 days at 26 O C to develop.<br />

Candida albicans also produces characteristic large, round, terminal, thick-walled vesicles<br />

(often called chlamydospores). The key features to remember are to use a light<br />

inoculum and to scratch the surface of the agar with the wire when inoculating.<br />

(b) Physiological and biochemical tests including fermentation and assimilation studies<br />

should be performed based on those used at the Centraalbureau voor Schimmelcultures,<br />

Utrecht, The Netherlands. Reference “The Yeasts: a taxonomic study”, edited<br />

by Kurtzman and Fell (1998), Elsevier Science Publishers B.V. Amsterdam. Reliable<br />

commercially available yeast identification kits are the API 20C, ID32C, MicroScan and<br />

Vitek systems. For specific identification of species see appropriate text book.<br />

5 mm 10 μm<br />

a b<br />

(a) Dalmau plate culture showing colonies of C. albicans growing out from scratches<br />

on the surface of a cornmeal/tween 80 agar plate. Note: a coverslip has been placed<br />

onto the agar surface covering the scratches. (b) Confirmatory test for C. albicans.<br />

Production of large round, thick-walled vesicles (often called chlamydospores) in<br />

Dalmau plate cultures.<br />

For descriptions of species, keys to taxa and additional information see Barnett et al.<br />

(1983), Kurtzman and Fell (1988) and de Hoog et al. (2000).


22<br />

Descriptions of Medical Fungi<br />

Candida albicans (Robin) Berkhout<br />

10 μm<br />

10 μm<br />

CHROMagar Candida plate<br />

showing chromogenic colour<br />

change for C. albicans (green),<br />

C. tropicalis (blue), C. parapsilosis<br />

(white) and C. glabrata<br />

(pink).<br />

Candida albicans on Sabouraud’s<br />

dextrose agar showing<br />

typical cream coloured, smooth<br />

surfaced, waxy colonies.<br />

Direct smear of urine from a<br />

patient with candidiasis of the<br />

kidney showing C. albicans in<br />

mycelial or tissue phase with<br />

blastoconidia budding from the<br />

pseudohyphae.<br />

Microscopic morphology of<br />

C. albicans showing budding<br />

spherical to ovoid blastoconidia.


Descriptions of Medical Fungi 23<br />

Candida albicans (Robin) Berkhout<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical to subspherical budding blastoconidia, 2-7 x 3-8 µm in size.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Branched pseudohyphae<br />

with dense verticils of blastoconidia. Spherical chlamydospores, mostly terminal, often<br />

on a slightly swollen subtending cell are formed near the edge of the cover slip.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube + L-Sorbose v L-Arabinose v D-Glucitol -(s)<br />

Fermentation Sucrose v D-Arabinose v α-M-D-glucoside v<br />

Glucose + Maltose + D-Ribose -(s) D-Gluconate -(s)<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate +<br />

Sucrose -(s) Trehalose +(s) D-Glucosamine v myo-Inositol +<br />

Maltose + Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol v D-Glucuronate -<br />

Trehalose v Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose v Ribitol v Urease -<br />

Glucose + Soluble Starch + Galactitol - 0.1% Cycloheximide +<br />

Galactose + D-Xylose + D-Mannitol + Growth at 40 O C +<br />

Key Features: germ tube positive, production of chlamydospores on Dalmau plate<br />

culture, fermentation of glucose, sugar assimilation profile and a distinctive green<br />

colour on CHROMagar. Note: germ tube negative variants, known as C. claussenii,<br />

and sucrose-negative variants described as C. stellatoidea have proven to be<br />

synonymous with C. albicans. C. albicans is a commensal of mucous membranes<br />

and the gastrointestinal tract. Environmental isolations have been made from sources<br />

contaminated by human or animal excreta, such as polluted water, soil, air and plants.<br />

RG-2 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range MIC Range MIC 90 90<br />

Fluconazole 0.03->64 2 Amphotericin B 0.03-4 0.25<br />

Itraconazole 0.008->8 0.125 Flucytosine 0.03->64 0.5<br />

Posaconazole 0.008->8 0.016 Caspofungin 0.008->4 0.125<br />

Voriconazole 0.008->8 0.03 Anidulafungin 0.008->8 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2006, 2007),<br />

Espinel-Ingroff (2003), Hajjeh et al. (2004), Richter et al. (2005) and Cuenca-Estrella<br />

et al. (2006). MIC 90 s from the Australian Candidemia Study (nd = not done).


24<br />

Descriptions of Medical Fungi<br />

Candida colliculosa (Hartmann) S.A. Meyer & Yarrow<br />

Teleomorph: Torulaspora delbrueckii (Lindner) Lindner.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical to ellipsoidal budding blastoconidia, 2-6 x 3-7 µm in size. Ascospores<br />

may be produced on 5% malt extract or cornmeal agar after 5-30 days at<br />

25 O C.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Budding yeast cells only.<br />

No pseudohyphae or true hyphae produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose - D-Glucitol v<br />

Fermentation Sucrose v D-Arabinose - α-M-D-glucoside v<br />

Glucose + Maltose v D-Ribose - D-Gluconate v<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate v<br />

Sucrose v Trehalose -,s D-Glucosamine - myo-Inositol -<br />

Maltose v Lactose - N-A-D-glucosamine - 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol v D-Glucuronate v<br />

Trehalose v Raffinose v Erythritol - Nitrate -<br />

Assimilation Melezitose v Ribitol v Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose v D-Xylose v D-Mannitol + Growth at 37 O C v<br />

Key Features: asci containing 1-4 spheroidal ascospores, variable growth at 37 O C<br />

and a variable sugar assimilation profile. C. colliculosa is a rare cause of candidemia.<br />

RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole 8 Amphotericin B 0.25<br />

Itraconazole 0.25 Flucytosine 0.03<br />

Posaconazole 0.25 Caspofungin 0.06<br />

Voriconazole 0.06 Anidulafungin nd<br />

Very limited data, antifungal susceptibility testing of individual stains is recommended.<br />

Data from the Australian Candidemia Study (nd = not done).


Descriptions of Medical Fungi 25<br />

Candida dubliniensis Sullivan et al.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical to subspherical budding blastoconidia, 3-8 x 2-7 µm in size.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Branched pseudohyphae<br />

with dense verticils of blastoconidia and spherical, mostly terminal chlamydospores.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube + L-Sorbose - L-Arabinose - D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside +,s<br />

Glucose + Maltose + D-Ribose - D-Gluconate -,s<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate +<br />

Sucrose - Trehalose + D-Glucosamine -,s myo-Inositol -<br />

Maltose + Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose v Glycerol +,s D-Glucuronate -<br />

Trehalose v Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol +,s Urease -<br />

Glucose + Soluble Starch + Galactitol - 0.1% Cycloheximide +<br />

Galactose + D-Xylose v D-Mannitol + Growth at 40 O C +<br />

Key Features: germ tube positive, similar to C. albicans, except for absence of growth<br />

at 45 o C; glycerol (mostly +), methyl-α-D-glucoside (-), trehalose (-), and D-xylose (-).<br />

Initial colonies dark green colour on CHROMagar and producing rough colonies on<br />

bird seed agar. C. dubliniensis is an uncommon cause of candidemia and mucosal<br />

infection, especially in HIV patients. RG-2 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.05->64 1 Amphotericin B 0.03-2 0.125<br />

Itraconazole 0.008->8 0.125 Flucytosine 0.03-64 0.125<br />

Posaconazole 0.03-1 0.125 Caspofungin 0.008-1 0.25<br />

Voriconazole 0.008-2 0.016 Anidulafungin


26<br />

Descriptions of Medical Fungi<br />

Candida fabianii (Hartmann) S.A. Meyer & Yarrow<br />

Teleomorph: Pichia fabianii (Wickerham) Kurtzman<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spheroidal to ellipsoidal budding blastoconidia, 3.0-6.5 x 2-5.5 µm in<br />

size. No pseudohyphae produced. Asci when present spherical, containing 1-4 spherical,<br />

faintly roughened ascospores.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ovoid budding<br />

yeast cells and occasional pseudohyphae produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside +<br />

Glucose + Maltose + D-Ribose - D-Gluconate +<br />

Galactose - Cellobiose + L-Rhamnose - DL-Lactate +<br />

Sucrose + Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose +,s Lactose - N-A-D-glucosamine - 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose + Erythritol - Nitrate +<br />

Assimilation Melezitose + Ribitol - Urease -<br />

Glucose + Soluble Starch + Galactitol - 0.1% Cycloheximide -<br />

Galactose - D-Xylose + D-Mannitol + Growth at 37 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Molecular<br />

identification may be required. Candida fabianii is a rare cause of candidemia. RG-1<br />

organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range Range<br />

Fluconazole 8 Amphotericin B 0.125<br />

Itraconazole 0.5 Flucytosine 0.03<br />

Posaconazole 0.5 Caspofungin 0.5<br />

Voriconazole 0.125 Anidulafungin nd<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Data from the Australian Candidemia Study (nd = not done).


Descriptions of Medical Fungi 27<br />

Teleomorph: Debaryomyces hansenii (Zopf) Lodder & Kreger-van Rij.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoid to broadly ellipsoidal budding blastoconidia, 3.5-5 x 2-3.5 µm in<br />

size. No pseudohyphae produced. Asci when present spherical, persistent, containing<br />

1-2 spherical ascospores with rough walls.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ovoid budding<br />

yeast cells only. No pseudohyphae produced.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

famata is a common environmental isolate, however it is only rarely recovered from<br />

clinical specimens, usually associated with skin. RG-1 organism.<br />

Antifungal<br />

Candida famata (Harrison) S.A. Meyer & Yarrow<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose +,w D-Glucitol +,w<br />

Fermentation Sucrose + D-Arabinose v α-M-D-glucoside +<br />

Glucose -,w Maltose + D-Ribose v D-Gluconate +,w<br />

Galactose -,w Cellobiose + L-Rhamnose v DL-Lactate v<br />

Sucrose -,w Trehalose + D-Glucosamine v myo-Inositol -<br />

Maltose - Lactose v N-A-D-glucosamine v 2-K-D-gluconate +<br />

Lactose - Melibiose v Glycerol + D-Glucuronate v<br />

Trehalose -,w Raffinose + Erythritol v Nitrate -<br />

Assimilation Melezitose v Ribitol + Urease -<br />

Glucose + Soluble Starch v Galactitol v 0.1% Cycloheximide v<br />

Galactose + D-Xylose + D-Mannitol + Growth at 40 O C +,w<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole 0.125->64 Amphotericin B 0.06-2<br />

Itraconazole 0.03->8 Flucytosine 0.06-128<br />

Posaconazole 0.06-1 Caspofungin 0.06->16<br />

Voriconazole 0.03-1 Anidulafungin 0.008->16<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Pfaller et al. (2003, 2007), Espinel-Ingroff (2003),<br />

Cuenca-Estrella et al. (2006) and the Australian Candidemia Study.


28<br />

Descriptions of Medical Fungi<br />

Synonym: Torulopsis glabrata (Anderson) Lodder & de Vries<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoid to ellipsoidal budding blastoconidia, 3.4 x 2.0 µm in size. No pseudohyphae<br />

or chlamydospores produced.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Ovoid budding yeast cells<br />

only. No pseudohyphae produced.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida glabrata<br />

is one of the most common yeast species to be found on the body surface and<br />

is often isolated as an incidental finding from skin and urine. It has been implicated<br />

as an “opportunistic” cause of both superficial and systemic infections, especially in<br />

immunocompromised patients, and it has been isolated from patients with septicemia,<br />

pyelonephritis, pulmonary infections, endocarditis and hyperalimentation. Approximately<br />

10% of clinical isolates show azole cross resistance. RG-2 organism.<br />

Antifungal<br />

Candida glabrata (Anderson) S.A. Meyer & Yarrow<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose + Maltose - D-Ribose - D-Gluconate -<br />

Galactose - Cellobiose - L-Rhamnose - DL-Lactate -<br />

Sucrose - Trehalose - D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine - 2-K-D-gluconate v<br />

Lactose - Melibiose - Glycerol +,s D-Glucuronate -<br />

Trehalose v Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose - D-Xylose - D-Mannitol - Growth at 40 O C +<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.03->128 128 Amphotericin B 0.008-2 0.5<br />

Itraconazole 0.008->16 16 Flucytosine 0.008-16 0.03<br />

Posaconazole 0.008-8 8 Caspofungin 0.008->8 0.25<br />

Voriconazole 0.008-16 2 Anidulafungin 0.008-8 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2006, 2007),<br />

Espinel-Ingroff (2003), Hajjeh et al. (2004), Richter et al. (2005) and Cuenca-Estrella<br />

et al. (2006). MIC 90 s from the Australian Candidemia Study (note: in this study 10%<br />

of primary blood isolates were azole cross-resistant, nd = not done).


Descriptions of Medical Fungi 29<br />

Teleomorph: Pichia guilliermondii Wickerham.<br />

Culture: White to cream-coloured smooth, glabrous yeast-like colonies.<br />

Microscopy: Spherical to subspherical budding yeast-like cells or blastoconidia, 2.0-<br />

4.0 x 3.0-6.5 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Branched pseudohyphae<br />

with dense verticils of blastoconidia.<br />

Antifungal<br />

Candida guilliermondii (Castellani) Langeron & Guerra<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose v D-Glucitol v<br />

Fermentation Sucrose + D-Arabinose v α-M-D-glucoside v<br />

Glucose + Maltose + D-Ribose + D-Gluconate v<br />

Galactose v Cellobiose v L-Rhamnose v DL-Lactate v<br />

Sucrose + Trehalose + D-Glucosamine + myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose v Glycerol + D-Glucuronate -<br />

Trehalose + Raffinose + Erythritol - Nitrate -<br />

Assimilation Melezitose v Ribitol + Urease -<br />

Glucose + Soluble Starch - Galactitol v 0.1% Cycloheximide v<br />

Galactose + D-Xylose + D-Mannitol v Growth at 37 O C v<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

guilliermondii has been isolated from numerous human infections, mostly of cutaneous<br />

origin. It is also found from normal skin and in sea water, faeces of animals, fig wasps,<br />

buttermilk, leather, fish, and beer. RG-1 organism.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125->128 16 Amphotericin B 0.03-1 0.5<br />

Itraconazole 0.03-8 1.0 Flucytosine 0.03-8 0.125<br />

Posaconazole 0.03-8 0.5 Caspofungin 0.125->8 0.5<br />

Voriconazole 0.03-8 0.25 Anidulafungin 0.06-4 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2003, 2006, 2007),<br />

Espinel-Ingroff (2003) and Cuenca-Estrella et al. (2006). MIC 90 s from the Australian<br />

Candidemia Study (nd = not done).


30<br />

Descriptions of Medical Fungi<br />

Candida haemulonii (van Uden & Kolipinski) Meyer & Yarrow<br />

Synonym: Torulopsis haemulonii van Uden & Kolipinski<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoid to globose, budding yeast-like cells or blastoconidia, 3.0-5.0 x<br />

3.0-6.5 µm. No pseudohyphae produced.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ovoid, budding<br />

yeast-like cells only. No pseudohyphae produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose -,s D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose -,s α-M-D-glucoside -<br />

Glucose + Maltose + D-Ribose -,s D-Gluconate +<br />

Galactose - Cellobiose - L-Rhamnose +,s DL-Lactate -<br />

Sucrose + Trehalose + D-Glucosamine +,s myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol +,s D-Glucuronate -<br />

Trehalose +,s Raffinose +,s Erythritol - Nitrate -<br />

Assimilation Melezitose +,s Ribitol s Urease -<br />

Glucose + Soluble Starch v Galactitol -,s 0.1% Cycloheximide +<br />

Galactose -,s D-Xylose -,s D-Mannitol + Growth at 37 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Molecular<br />

identification may be required. Candida haemulonii has been reported from a few<br />

cases of fungemia but clinical isolations remain rare. It has also been isolated from<br />

fish and a dolphin. C. haemulonii may be difficult to distinguish from C. famata using<br />

some commercial yeast identification systems due to data base limitations. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

Range<br />

Fluconazole 32->256 Amphotericin B 2-8<br />

Itraconazole 0.125-4 Flucytosine 0.008-0.125<br />

Voriconazole 0.06-0.5 Caspofungin 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Rodero et al. (2002) and Khan et al. (2007).


Descriptions of Medical Fungi 31<br />

Candida inconspicua (Lodder & Kreger-van Rij) S.A.Meyer & Yarrow<br />

Synonym: Torulopsis inconspicua Lodder & Kreger-van Rij.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoidal budding blastoconidia, 2.0-5 x 5.0-11.0 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ovoid budding<br />

yeast cells only. Primitive pseudohyphae may be produced after 14 days.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose - Maltose - D-Ribose - D-Gluconate -<br />

Galactose - Cellobiose - L-Rhamnose - DL-Lactate +<br />

Sucrose - Trehalose - D-Glucosamine + myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine + 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose - D-Xylose - D-Mannitol - Growth at 40 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

inconspicua is a rare cause of candidemia. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole 4-128 Amphotericin B 0.125->8<br />

Itraconazole 0.25-8 Flucytosine 1-64<br />

Posaconazole 0.5-8 Caspofungin 0.008-0.25<br />

Voriconazole 0.125-4 Anidulafungin nd<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Pfaller et al. (2003), Espinel-Ingroff (2003) and the Australian Candidemia Study (nd<br />

= not done).


32<br />

Descriptions of Medical Fungi<br />

Synonym: Candida pseudotropicalis (Castellani) Basgal.<br />

Teleomorph: Kluyveromyces marxianus (Hansen) van der Walt.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Short-ovoid to long-ovoid, budding blastoconidia, 3.0-6.5 x 5.5-11.0 µm,<br />

sometimes becoming elongate (up to 16.0 µm).<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Abundant, long, wavy,<br />

branched pseudohyphae usually formed, with ovoid blastoconidia, budding off singly,<br />

in pairs or chains, often in a verticillated position. Note: in some strains pseudohyphae<br />

may be scarce or almost absent.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

kefyr is a rare cause of candidiasis and is usually associated with superficial cutaneous<br />

manifestations rather than systemic disease. Environmental isolations have been<br />

made from cheese and dairy products. RG-1 organism.<br />

Antifungal<br />

Candida kefyr (Beijerinck) van Uden & Buckley<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose v D-Glucitol v<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside -<br />

Glucose + Maltose - D-Ribose v D-Gluconate -<br />

Galactose +,s Cellobiose v L-Rhamnose - DL-Lactate +<br />

Sucrose + Trehalose -,w D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose v N-A-D-glucosamine - 2-K-D-gluconate -<br />

Lactose v Melibiose - Glycerol s D-Glucuronate -<br />

Trehalose - Raffinose + Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol s Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide +<br />

Galactose s D-Xylose s D-Mannitol v Growth at 40 O C +<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125-4 0.5 Amphotericin B 0.125->8 1<br />

Itraconazole 0.03-0.5 0.06 Flucytosine 0.03-64 16<br />

Posaconazole 0.03-0.25 0.25 Caspofungin 0.03-1 0.125<br />

Voriconazole 0.008-0.125 0.016 Anidulafungin 0.03-0.5 nd<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Pfaller et al. (2003, 2006), Espinel-Ingroff (2003) and<br />

Cuenca-Estrella et al. (2006). MIC 90 s from the Australian Candidemia Study (nd =<br />

not done).


Descriptions of Medical Fungi 33<br />

Teleomorph: Issatchenkia orientalis Kudryavtesev.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Predominantly small, elongated to ovoid budding blastoconidia, 2.0-5.5<br />

x 4.0-15.0 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Abundant long, wavy,<br />

branched pseudohyphae with elongated to ovoid blastoconidia, budding off in verticillate<br />

branches.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

krusei is regularly associated with some forms of infant diarrhoea and occasionally<br />

with systemic disease. It has also been reported to colonise the gastrointestinal, respiratory<br />

and urinary tracts of patients with granulocytopenia. Environmental isolations<br />

have been made from beer, milk products, skin, faeces of animals and birds and pickle<br />

brine. RG-2 organism.<br />

Antifungal<br />

Candida krusei (Castellani) Berkhout<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose + Maltose - D-Ribose - D-Gluconate -<br />

Galactose - Cellobiose - L-Rhamnose - DL-Lactate +<br />

Sucrose - Trehalose - D-Glucosamine + myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine + 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide v<br />

Galactose - D-Xylose - D-Mannitol - Growth at 40 O C +<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.25->128 64 Amphotericin B 0.06->8 1<br />

Itraconazole 0.03->8 0.5 Flucytosine 0.5-64 16<br />

Posaconazole 0.03-1 1 Caspofungin 0.125->4 1<br />

Voriconazole 0.03-4 0.5 Anidulafungin 0.008-8 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2003, 2007),<br />

Espinel-Ingroff (2003), Hajjeh et al. (2004), Richter et al. (2005) and Cuenca-Estrella<br />

et al. (2006). MIC 90 s from the Australian Candidemia Study (nd = not done).


34<br />

Descriptions of Medical Fungi<br />

Candida lipolytica (F.C. Harrison) Diddens & Lodder<br />

Teleomorph: Yarrowia lipolytica (Wickerham et al.) van der Walt & von Arx.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical, ellipsoidal to elongate budding blastoconidia, 3.0-5 x 3.3-15.0<br />

µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Pseudohyphae and true<br />

hyphae are produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose - D-Glucitol +<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose - Maltose - D-Ribose v D-Gluconate v<br />

Galactose - Cellobiose w,- L-Rhamnose - DL-Lactate +<br />

Sucrose - Trehalose - D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine + 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol + Nitrate -<br />

Assimilation Melezitose - Ribitol v Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose v D-Xylose - D-Mannitol + Growth at 37 O C v<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

lipolytica is a rare cause of candidemia. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole 1->64 Amphotericin B 0.06-1<br />

Itraconazole 0.06-8 Flucytosine 0.125-64<br />

Posaconazole 0.03-4 Caspofungin 0.25-2<br />

Voriconazole 0.03-1 Anidulafungin 0.125-0.5<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Pfaller et al. (2003), Espinel-Ingroff (2003) and Australian<br />

Candidemia Study.


Descriptions of Medical Fungi 35<br />

Candida lusitaniae van Uden & do Carmo-Sousa<br />

Teleomorph: Clavispora lusitaniae Rodrigues de Miranda.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoid to ellipsoidal budding blastoconidia, 1.5-6.0 x 2.5-10.0 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Abundant pseudohyphae<br />

with short chains of blastoconidia.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose + L-Arabinose v D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside v<br />

Glucose + Maltose + D-Ribose - D-Gluconate s<br />

Galactose v Cellobiose + L-Rhamnose v DL-Lactate +,w<br />

Sucrose v Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose v Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose v Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol s Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose + D-Xylose + D-Mannitol + Growth at 40 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

lusitaniae is a known cause of disseminated candidiasis, including septicemia and<br />

pyelonephritis. C. lusitaniae was first isolated from the alimentary tract of warm blooded<br />

animals and environmental isolations have been made from cornmeal, citrus peel,<br />

fruit juices, and milk from cows with mastitis. C. lusitaniae may also be difficult to distinguish<br />

from C. tropicalis using some yeast identification systems. RG-2 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125-64 8 Amphotericin B 0.03-8 0.125<br />

Itraconazole 0.06-2 0.125 Flucytosine 0.03-128 0.03<br />

Posaconazole 0.008-0.5 0.25 Caspofungin 0.125-4 0.5<br />

Voriconazole 0.008-2 0.125 Anidulafungin 0.03->8 nd<br />

Some data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2003),<br />

Espinel-Ingroff (2003) and Cuenca-Estrella et al. (2006). MIC 90 s from the Australian<br />

Candidemia Study (nd = not done).


36<br />

Descriptions of Medical Fungi<br />

Candida norvegensis Dietrichson ex van Uden & Buckley<br />

Teleomorph: Pichia norvegensis Leask & Yarrow.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ovoid, budding blastoconidia, 2.0-3.5 x 3.5-5.0 µm. Pseudohyphae<br />

rarely produced.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ovoid budding<br />

yeast cells only. No pseudohyphae produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose s Maltose - D-Ribose - D-Gluconate -<br />

Galactose - Cellobiose + L-Rhamnose - DL-Lactate w<br />

Sucrose - Trehalose - D-Glucosamine + myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine - 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose - D-Xylose - D-Mannitol - Growth at 37 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

norvegensis is a very rare clinical isolate that has been reported as a causative agent<br />

of peritonitis and disseminated candidiasis in a patient on CAPD. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

Range<br />

Fluconazole 16 Amphotericin B 1<br />

Itraconazole 0.25 Flucytosine 8<br />

Voriconazole 0.125 Posaconazole 0.125<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Pfaller et al. (2002b).


Descriptions of Medical Fungi 37<br />

Candida parapsilosis Complex<br />

Recently Candida parapsilosis has been recognised as 3 species: C. parapsilosis, C.<br />

orthopsilosis and C. metapsilosis (Tavanti et al. 2005). These three species are phenotypically<br />

indistinguishable and are best distinguished by genetic analysis. Antifungal<br />

susceptibility data from the Australian Candidemia Study also shows no significant differences<br />

between the species.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Predominantly small, globose to ovoid budding blastoconidia, 2.0-3.5 x<br />

3.0-4.5 µm, with some larger elongated forms present.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Abundant, much-branched<br />

pseudohyphae in a delicate tree-like pattern with 2-3 blastoconidia in small clusters at<br />

intervals along the pseudohyphae.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose +,s L-Arabinose + D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside +<br />

Glucose + Maltose + D-Ribose v D-Gluconate +,s<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate -<br />

Sucrose -,s Trehalose + D-Glucosamine v myo-Inositol -<br />

Maltose -,s Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose -,s Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol +,s Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose + D-Xylose + D-Mannitol + Growth at 37 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

parapsilosis is an opportunistic human pathogen which may cause cutaneous infections,<br />

especially of the nail and systemic disease, especially endocarditis. Other clinical<br />

manifestations include endophthalmitis and fungemia. Environmental isolations have<br />

been made from intertidal and oceanic waters, pickle brine, cured meats, olives and<br />

normal skin, and faeces. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125->64 8 Amphotericin B 0.016-2 0.5<br />

Itraconazole 0.015-2 0.25 Flucytosine 0.03->64 0.25<br />

Posaconazole 0.008-0.5 0.03 Caspofungin 0.03->8 1<br />

Voriconazole 0.008-2 0.25 Anidulafungin 0.008->8 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2006, 2007),<br />

Espinel-Ingroff (2003), Hajjeh et al. (2004), Richter et al. (2005) and Cuenca-Estrella<br />

et al. (2006). MIC 90 s from the Australian Candidemia Study (nd = not done).


38<br />

Descriptions of Medical Fungi<br />

Candida pelliculosa Redaelli<br />

Teleomorph: Pichia anomala (Hansen) Kurtzman.<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical to ellipsoidal budding blastoconidia, 2-4 x 2-6 µm. Pseudohyphae<br />

may be present. Asci when present, containing 1-4 hat-shaped ascospores.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Spherical to ellipsoidal<br />

budding yeast cells and abundant pseudohyphae in most strains.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose v D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside +<br />

Glucose + Maltose + D-Ribose v D-Gluconate v<br />

Galactose v Cellobiose + L-Rhamnose - DL-Lactate +<br />

Sucrose + Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose v Lactose - N-A-D-glucosamine - 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate n<br />

Trehalose - Raffinose + Erythritol + Nitrate +<br />

Assimilation Melezitose + Ribitol v Urease -<br />

Glucose + Soluble Starch + Galactitol - 0.1% Cycloheximide -<br />

Galactose v D-Xylose v D-Mannitol + Growth at 37 O C v<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

pelliculosa has been reported from cases of candidemia and catheter related infections<br />

in humans and has been isolated from soil, grains, fruit and warm blooded animals.<br />

RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range<br />

Antifungal<br />

Range<br />

Fluconazole 2-16 Amphotericin B 0.125-2<br />

Itraconazole 0.25-2 Flucytosine 0.03-64<br />

Posaconazole 0.125-1 Caspofungin 0.06-0.5<br />

Voriconazole 0.06-0.25 Anidulafungin nd<br />

Limited data available, antifungal susceptibility testing of individual strains is<br />

recommended. Pfaller et al. (2003), Espinel-Ingroff (2003), Cuenca-Estrella et al.<br />

(2006) and the Australian Candidemia Study (nd = not done).


Descriptions of Medical Fungi 39<br />

Candida rugosa (Anderson) Diddens & Lodder<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Ellipsoidal to elongate budding blastoconidia, 6-10 x 2-3.5 µm. Sometimes<br />

short pseudohyphae may be produced.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Ellipsoidal budding yeast<br />

cells only and densely branched pseudohyphae produced.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose - D-Glucitol +,s<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose - Maltose - D-Ribose - D-Gluconate v<br />

Galactose - Cellobiose - L-Rhamnose - DL-Lactate +,s<br />

Sucrose - Trehalose - D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine s 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol -,s Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose + D-Xylose v D-Mannitol +,s Growth at 37 O C +<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

rugosa has been associated with catheter related fungemia and has been isolated<br />

from human and bovine faeces, sea water and soil. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole 1-16 Amphotericin B 0.25-4<br />

Itraconazole 0.03-1 Flucytosine 0.06-16<br />

Posaconazole 0.06-0.25 Caspofungin 0.25-2<br />

Voriconazole 0.008-0.25 Anidulafungin 0.03-4<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Pfaller et al. (2003), Espinel-Ingroff (2003) and the<br />

Australian Candidemia Study.


40<br />

Descriptions of Medical Fungi<br />

Culture: Colonies (SDA) white to cream-coloured smooth, glabrous yeast-like.<br />

Microscopy: Spherical to subspherical budding yeast-like cells or blastoconidia, 3-5.5<br />

x 4-9 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Abundant, long, wavy,<br />

branched pseudohyphae with numerous ovoid blastoconidia, budding off. Terminal<br />

vesicles (chlamydospores) are not produced.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Candida<br />

tropicalis is a major cause of septicemia and disseminated candidiasis. It is also found<br />

as part of the normal human mucocutaneous flora and environmental isolations have<br />

been made from faeces, shrimp, kefir, and soil. RG-2 organism.<br />

Antifungal<br />

Candida tropicalis (Castellani) Berkhout<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose - D-Glucitol +<br />

Fermentation Sucrose v D-Arabinose - α-M-D-glucoside v<br />

Glucose + Maltose + D-Ribose -,s D-Gluconate v<br />

Galactose + Cellobiose +,s L-Rhamnose - DL-Lactate v<br />

Sucrose v Trehalose + D-Glucosamine v myo-Inositol -<br />

Maltose + Lactose - N-A-D-glucosamine + 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol v D-Glucuronate -<br />

Trehalose +,s Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose v Ribitol +,s Urease -<br />

Glucose + Soluble Starch + Galactitol - 0.1% Cycloheximide +<br />

Galactose + D-Xylose + D-Mannitol + Growth at 40 O C +<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125->128 2 Amphotericin B 0.03-8 0.5<br />

Itraconazole 0.03->8 0.5 Flucytosine 0.03->64 0.125<br />

Posaconazole 0.008->8 0.06 Caspofungin 0.03->8 0.25<br />

Voriconazole 0.008->8 0.25 Anidulafungin 0.03->8 nd<br />

Good data available. Espinel-Ingroff et al. (2001), Pfaller et al. (2002b, 2006, 2007),<br />

Espinel-Ingroff (2003), Hajjeh et al. (2004), Richter et al. (2005) and Cuenca-Estrella<br />

et al. (2006). MIC 90 s from the Australian Candidemia Study (nd = not done).


Descriptions of Medical Fungi 41<br />

Chaetomium Kunze ex Fries<br />

This genus is a common ascomycete (pyrenomycete) characterised by the formation of<br />

darkly-pigmented, globose, ovoid, barrel to flask-shaped, ostiolate ascocarps (perithecia)<br />

beset with dark-coloured terminal hairs (setae) which are straight, branched or<br />

curved. Asci are clavate to cylindrical, typically eight-spored and evanescent. Ascospores<br />

are one-celled, darkly-pigmented, smooth-walled, of varying shape, mostly<br />

ovoid, ellipsoidal or lemon-shaped. Chlamydospores and solitary conidia may also be<br />

produced. RG-1 organism.<br />

The genus contains between 160 and 180 species, and all are saprophytic being isolated<br />

from soil, straw, dung and plant debris. However, quite a few species are thermophilic<br />

and can grow at temperatures above 37 O C. Chaetomium species are important<br />

agents for the decomposition of cellulose waste and plant materials, and are only<br />

rarely isolated in medical mycology laboratories.<br />

Key Features: ascomycete producing darkly-pigmented ostiolate perithecia beset with<br />

long dark terminal setae.<br />

For descriptions of species, keys to taxa and additional information see Ames (1963),<br />

Seth (1970), Millner (1975), Domsch et al. (1980), Ellis and Keane (1981), Ellis (1981)<br />

and de Hoog et al. (2000).<br />

100 μm<br />

10 μm<br />

Ascocarp (perithecia), terminal hairs, asci and ascospores of Chaetomium.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-16 Itraconazole 0.03-0.125 Voriconazole 0.125-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


42<br />

Descriptions of Medical Fungi<br />

Chrysosporium Corda<br />

Colonies are moderately fast growing, flat, white to tan to beige in colour, often with a<br />

powdery or granular surface texture. Reverse pigment absent or pale brownish-yellow<br />

with age. Hyaline, one-celled conidia are produced directly on vegetative hyphae<br />

by non-specialised conidiogenous cells. Conidia are typically pyriform to clavate with<br />

truncate bases and are formed either intercalary (arthroconidia), laterally (often on<br />

pedicels) or terminally.<br />

Species of Chrysosporium are occasionally isolated from skin and nail scrapings, especially<br />

from feet, but because they are common soil saprophytes they are usually<br />

considered as contaminants. There are about 22 species of Chrysosporium, several<br />

are keratinolytic with some also being thermotolerant, and cultures may closely resemble<br />

some dermatophytes, especially Trichophyton mentagrophytes, and some strains<br />

may also resemble cultures of Histoplasma and Blastomyces.<br />

Chrysosporium tropicum Carmichael<br />

Colonies are flat, white to cream-coloured with a very granular surface. Reverse pigment<br />

absent or pale brownish-yellow with age. Microscopically, conidia are numerous,<br />

hyaline, single-celled, clavate to pyriform, smooth, slightly thick-walled (6-7 x 3.5-4<br />

µm), and have broad truncate bases and pronounced basal scars. The conidia are<br />

formed at the tips of the hyphae, on short or long lateral branches, or sessile along the<br />

hyphae (intercalary). No macroconidia or hyphal spirals are seen. RG-2 organism.<br />

For descriptions of species, keys to taxa and additional information see Carmichael<br />

(1962), Rebell and Taplin (1970), Sigler and Carmichael (1976), Van Oorschot (1980),<br />

Domsch et al. (1980) and de Hoog et al. (2000).<br />

10 μm<br />

Chrysosporium tropicum showing typical pyriform to clavate-shaped conidia<br />

with truncated bases which may be formed either intercalary, laterally<br />

or terminally.


Descriptions of Medical Fungi 43<br />

Cladophialophora bantiana (Saccardo) de Hoog et al.<br />

Synonym: Xylohypha bantiana (Saccardo) McGinnis, Borelli and Ajello<br />

Colonies are moderately fast growing, olivaceous-grey, suede-like to floccose and<br />

grow at temperatures up to 42-43 O C. Conidia are formed in long, sparsely branched,<br />

flexuose, acropetal chains from undifferentiated conidiophores. Conidia are one-celled<br />

(very occasionally two-celled), pale brown, smooth-walled, ellipsoid to oblong-ellipsoid<br />

and are 2-3 x 4-7 µm in size.<br />

Cladophialophora bantiana has been isolated from soil and is a recognised agent of<br />

cerebral phaeohyphomycosis. The fungus is neurotropic and may cause brain abscesses<br />

in both normal and immunosuppressed patients. RG-2 organism.<br />

Cladophialophora bantiana may be distinguished from Cladosporium species by the<br />

absence of conidia with distinctly pigmented hila, the absence of characteristic shield<br />

cells and by growth at 42 O C (compared with Cladophialophora carrionii which has a<br />

maximum growth temperature of 35-36 O C, and Cladosporium species which have a<br />

maximum of less than 35 O C).<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), McGinnis and Borelli (1981), McGinnis et al. (1986a), Rippon (1988), Kwon-<br />

Chung and Bennett (1992) and de Hoog et al. (2000).<br />

10 μm<br />

Conidiophore and conidia of Cladophialophora bantiana.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.03-2 0.5 Posaconazole 0.008-0.06 0.06<br />

Itraconazole 0.03-0.5 0.5 Voriconazole 0.03-1 0.125<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001), Espinel-Ingroff (2001)<br />

and WCH in-house data.


44<br />

Descriptions of Medical Fungi<br />

Cladophialophora carrionii (Trejos) de Hoog et al.<br />

Synonym: Cladosporium carrionii Trejos<br />

Colonies are slow growing, reaching 3-4 cm in diameter after one month, with a compact<br />

suede-like to downy surface and are olivaceous-black in colour. Microscopy shows<br />

ascending to erect, olivaceous-green, apically branched, elongate conidiophores<br />

producing branched acropetal chains of smooth-walled conidia. Conidia are pale<br />

olivaceous, smooth-walled or slightly verrucose, limoniform to fusiform, 1.5-3.0 x 2.0-<br />

7.0 µm in size. Bulbous phialides with large collarettes and minute, hyaline conidia<br />

are occasionally formed on nutritionally poor media. Maximum growth temperature<br />

35-37 O C. RG-2 organism.<br />

Cladophialophora carrionii is a recognised agent of chromoblastomycosis and it<br />

has been isolated from soil and fence posts made from Eucalyptus sp. Cases of<br />

chromoblastomycosis caused by C. carrionii are commonly found in Australia,<br />

Venezuela, Madagascar and South America. Isolates from phaeomycotic cysts and<br />

opportunistic infections have also been reported.<br />

Key Features: conidia are smaller and comprise heavily branched systems which fall<br />

apart much more easily than in the other Cladophialophora species.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Rippon (1988), de Hoog et al. (1995) and de Hoog et al. (2000).<br />

10 μm<br />

Conidiophores and conidia of Cladophialophora carrionii.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.06-4 1 Posaconazole 0.06-0.5 0.25<br />

Itraconazole 0.03-0.5 0.5 Voriconazole 0.03-0.5 0.25<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001), Gonzales et al. (2005)<br />

and WCH in-house data.


Descriptions of Medical Fungi 45<br />

Cladosporium Link ex Fries<br />

Colonies are rather slow growing, mostly olivaceous-brown to blackish brown but also<br />

sometimes grey, buff or brown, suede-like to floccose, often becoming powdery due<br />

to the production of abundant conidia. Vegetative hyphae, conidiophores and conidia<br />

are equally pigmented. Conidiophores are more or less distinct from the vegetative<br />

hyphae, being erect, straight or flexuose, unbranched or branched only in the apical<br />

region, with geniculate sympodial elongation in some species. Conidia are produced in<br />

branched acropetal chains, being smooth, verrucose or echinulate, one- to four-celled,<br />

and have a distinct dark hilum. The term blastocatenate is often used to describe<br />

chains of conidia where the youngest conidium is at the apical or distal end of the chain.<br />

Note: the conidia closest to the conidiophore, and where the chains branch, are usually<br />

“shield-shaped”. The presence of shield-shaped conidia, a distinct hilum, and chains<br />

of conidia that readily disarticulate, are diagnostic for the genus Cladosporium.<br />

Cladosporium species have a world-wide distribution and are amongst the most common<br />

of air-borne fungi. Some 500 species have been described. Isolates of Cladosporium<br />

are frequently isolated as contaminants. RG-1 organisms. The pathogenic species<br />

have now been transferred to the genus Cladophialophora.<br />

Key Features: dematiaceous hyphomycete forming branched acropetal chains of<br />

conidia, each with a distinct hilum.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971 and<br />

1976), Domsch et al. (1980), McGinnis (1980) and de Hoog et al. (2000).<br />

Antifungal<br />

10 μm<br />

Conidiophores and conidia of Cladosporium cladosporioides.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-8 Itraconazole 0.03-32 Voriconazole 0.06-1<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


46<br />

Descriptions of Medical Fungi<br />

Coccidioides immitis/posadasii complex<br />

Recently Coccidioides immitis has been recognised as 2 species: C. immitis and C.<br />

posadasii (Fisher et al. 2002). The two species are morphologically identical and can<br />

be distinguished only by genetic analysis and different rates of growth in the presence<br />

of high salt concentrations (C. posadasii grows more slowly). C. immitis is geographically<br />

limited to California’s San Joaquin Valley region, whereas C. posadasii is found in<br />

the desert regions of the USA southwest, Mexico and South America. The two species<br />

appear to coexist in the desert regions of the USA southwest and Mexico.<br />

Colonies of C. immitis/posadasii on Sabouraud’s dextrose agar at 25 O C are initially<br />

moist and glabrous, but rapidly become suede-like to downy, greyish white with a tan<br />

to brown reverse, however considerable variation in growth rate and culture morphology<br />

has been noted. Microscopy shows typical single-celled, hyaline, rectangular to<br />

barrel-shaped, alternate arthroconidia, 2.5-4 x 3-6 µm in size, separated from each<br />

other by a disjunctor cell. This arthroconidial state has been classified in the genus<br />

Malbranchea and is similar to that produced by many non-pathogenic soil fungi, e.g.<br />

Gymnoascus species.<br />

WARNING: RG-3 organism. Cultures of Coccidioides immitis/posadasii represent a<br />

severe biohazard to laboratory personnel and must be handled with extreme caution in<br />

an appropriate pathogen handling cabinet. C. immitis/posadasii is a dimorphic fungus,<br />

existing in living tissue as spherules and endospores, and in soil or culture in a mycelial<br />

form. Culture identification by exoantigen test is now the method of choice.<br />

Key Features: clinical history, tissue pathology, culture identification by positive<br />

exoantigen test.<br />

20 μm<br />

Tissue morphology showing typical endosporulating spherules of C. immitis. Young<br />

spherules have a clear centre with peripheral cytoplasm and a prominent thick-wall.<br />

Endospores (sporangiospores) are later formed within the spherule by repeated cytoplasmic<br />

cleavage. Rupture of the spherule releases endospores into the surrounding<br />

tissue where they re-initiate the cycle of spherule development.


Descriptions of Medical Fungi 47<br />

Coccidioides immitis/posadasii complex<br />

5 μm<br />

Culture and arthroconidia separated from each other by disjunctor<br />

cells of Coccidioides immitis/posadasii.<br />

For descriptions of species, keys to taxa and additional information see Ajello (1957),<br />

Steele et al. (1977), McGinnis (1980), Chandler et al. (1980), Catanzaro (1986), Rippon<br />

(1988), de Hoog et al. (2000) and Fisher et al. (2002).<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.06-2 1 Posaconazole 0.03-1 0.5<br />

Fluconazole 2-64 32 Voriconazole 0.03-1 0.5<br />

Itraconazole 0.03-2 0.5<br />

Limited data available. Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003), Gonzalez<br />

et al. (2005) and Sabatelli et al. (2006).


48<br />

Descriptions of Medical Fungi<br />

Colletotrichum coccodes (Wallroth) S. Hughes<br />

Colonies usually darkly pigmented with white aerial mycelium, consisting of numerous<br />

black sclerotia and light brown-coloured conidial masses, reverse is dark brown.<br />

Sclerotia are usually abundant, setose, spherical and are often confluent. Conidia are<br />

straight, fusiform, attenuated at the ends, 16-22 x 3-4 µm. Appressoria are common,<br />

clavate, brown, 11-16.5 x 6-9.5 µm, variable in shape. RG-1 organism.<br />

Over 500 Colletotrichum species have been reported. C. coccodes is a common soil<br />

and plant pathogen widely distributed in Africa, Asia, Australasia, Europe, and the<br />

Americas. It has been reported from a case of human mycotic keratitis.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980) and de Hoog et al. (2000).<br />

20 μm<br />

10 μm<br />

50 μm<br />

Sclerotia with setae, conidia and appressoria of C. coccodes.


Descriptions of Medical Fungi 49<br />

Synonym: Entomophthora coronata (Costantin) Kevorkian<br />

The species of the genus Conidiobolus produce characteristic multinucleate primary<br />

and secondary (replicative) conidia on top of unbranched conidiophores. Each subspherical<br />

conidium is discharged as a result of the pressure developed within the conidium,<br />

and each bears a more or less prominent papilla after discharge (King 1983).<br />

The genus contains 27 species, however C. coronatus and C. incongruus are the only<br />

species that are known to cause human disease, although C. lamprauges has also<br />

been reported once from a horse (Humber, Brown and Kornegay, 1989).<br />

Colonies of C. coronatus grow rapidly and are flat, cream-coloured, glabrous becoming<br />

radially folded and covered by a fine, powdery, white surface mycelium and conidiophores.<br />

The lid of the petri dish soon becomes covered with conidia, which are<br />

forcibly discharged by the conidiophores. The colour of the colony may become tan to<br />

brown with age. Conidiophores are simple forming solitary, terminal conidia which are<br />

spherical, 10 to 25 µm in diameter, single-celled and have a prominent papilla. Conidia<br />

may also produce hair-like appendages, called villae. Conidia germinate to produce<br />

either, (1) single or multiple hyphal tubes that may also become conidiophores which<br />

bear secondary conidia, or (2) replicate by producing multiple short conidiophores,<br />

each bearing a small secondary conidium. RG-2 organism.<br />

Conidiobolus coronatus is commonly present in soil and decaying leaves. It has a<br />

world-wide distribution especially tropical rain forests of Africa. Human infections are<br />

usually restricted to the rhinofacial area. However, there are occasional reports of<br />

dissemination to other sites. All human infections have been confined to the tropics.<br />

For descriptions of species, keys to taxa and additional information see Emmons and<br />

Bridges (1961), King (1976a, 1976b, 1983), McGinnis (1980), Rippon (1988), Kwon-<br />

Chung and Bennett (1992), de Hoog et al. (2000) and Ellis (2005a).<br />

10 μm<br />

Conidiobolus coronatus (Costantin) Batko<br />

10 μm<br />

Spherical conidia with hair-like appendages (villae) and prominent papillae<br />

characteristic of Conidiobolus coronatus.


50<br />

Descriptions of Medical Fungi<br />

Cryptococcus Kützing emend. Phaff & Spencer<br />

The genus Cryptococcus is characterised by globose to elongate yeast-like cells or<br />

blastoconidia that reproduce by multilateral budding, by polar budding on a narrow<br />

base (may or may not be present), and pseudohyphae being absent or rudimentary.<br />

Most strains have capsulated cells; extent of capsule formation depends on the medium.<br />

Under certain conditions of growth the capsule may contain starch-like compounds,<br />

which are released into the medium by many strains. On solid media the<br />

cultures are generally mucoid or slimy in appearance; red, orange or yellow carotenoid<br />

pigments may be produced, but young colonies of most species are usually non-pigmented,<br />

being cream in colour. No fermentation: Nitrate assimilated or not: Inositol<br />

assimilated. The genus Cryptococcus is similar to the genus Rhodotorula. The distinctive<br />

difference between the two is the assimilation of inositol, which is positive in<br />

Cryptococcus.<br />

Cryptococcosis is a chronic, subacute to acute pulmonary, systemic or meningitic disease,<br />

initiated by the inhalation of basidiospores and/or desiccated yeast cells of Cryptococcus<br />

species. Primary pulmonary infections have no diagnostic symptoms and<br />

are usually subclinical. On dissemination, the fungus usually shows a predilection for<br />

the central nervous system, however skin, bones and other visceral organs may also<br />

become involved. Although C. neoformans and C. gattii are regarded as the principle<br />

pathogenic species, Cryptococcus albidus and Cryptococcus laurentii have on occasion<br />

also been implicated in human infection.<br />

5 μm<br />

Culture appearances on Bird Seed Agar of Cryptococcus neoformans (brown<br />

colonies) and Candida albicans (white colonies) and India ink preparation of<br />

C. neoformans surrounded by a characteristic wide gelatinous capsule.<br />

For descriptions of species, keys to taxa and additional information see Rippon (1982),<br />

Barnett et al. (1983), McGinnis (1980), Kurtzman and Fell (1988), Casadevall and Perfect<br />

(1988) and de Hoog et al. (2000).


Descriptions of Medical Fungi 51<br />

Cryptococcus albidus (Saito) Skinner<br />

Culture: Colonies (SDA) are cream-coloured smooth, mucoid glabrous yeast-like.<br />

Budding yeast cells only. No pseudohyphae present.<br />

Microscopy: Globose to ovoid budding yeast-like cells, 3.5-8.8 x 5.5-10.2 μm.<br />

India Ink Preparation: Positive - Distinct capsules are present.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose + D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose v α-M-D-glucoside v<br />

Glucose - Maltose + D-Ribose v D-Gluconate +<br />

Galactose - Cellobiose + L-Rhamnose v DL-Lactate v<br />

Sucrose - Trehalose +,w D-Glucosamine - myo-Inositol +<br />

Maltose - Lactose v N-A-D-glucosamine - 2-K-D-gluconate +<br />

Lactose - Melibiose v Glycerol v D-Glucuronate +<br />

Trehalose - Raffinose + Erythritol v Nitrate +<br />

Assimilation Melezitose + Ribitol v Urease +<br />

Glucose + Soluble Starch v Galactitol v 0.1% Cycloheximide -<br />

Galactose v D-Xylose + D-Mannitol + Growth at 37 O C v<br />

C. albidus has variable growth at 37 O C, and rare human infections have been reported<br />

however its pathogenicity is questionable. RG-1 organism.<br />

Cryptococcus laurentii (Kufferath) Skinner<br />

Culture: Colonies (SDA) are cream-coloured, often becoming a deeper orange-yellow<br />

with age, with a smooth mucoid texture. Budding yeast cells only. No pseudohyphae<br />

present.<br />

Microscopy: Spherical and elongated budding yeast-like cells or blastoconidia, 2.0-<br />

5.5 x 3.0-7.0 μm. No pseudohyphae present.<br />

India Ink Preparation: Positive - Narrow but distinct capsules are present.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose + D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose + α-M-D-glucoside +<br />

Glucose - Maltose + D-Ribose + D-Gluconate +<br />

Galactose - Cellobiose + L-Rhamnose + DL-Lactate v<br />

Sucrose - Trehalose + D-Glucosamine - myo-Inositol +<br />

Maltose - Lactose + N-A-D-glucosamine - 2-K-D-gluconate +<br />

Lactose - Melibiose + Glycerol v D-Glucuronate +<br />

Trehalose - Raffinose + Erythritol v Nitrate -<br />

Assimilation Melezitose + Ribitol + Urease +<br />

Glucose + Soluble Starch v Galactitol + 0.1% Cycloheximide -<br />

Galactose v D-Xylose + D-Mannitol + Growth at 37 O C -,w<br />

Note: some strains of C. laurentii may develop a brown pigment on Bird Seed agar and<br />

turn CGB media blue, similar to C. gattii, however C. laurentii assimilates both lactose<br />

and melibiose while C. gattii does not. Rare human infections have been reported<br />

however its pathogenicity is questionable. RG-1 organism.


52<br />

Descriptions of Medical Fungi<br />

Cryptococcus gattii (Vanbreus. & Takashio) Kwon-Chung & Boekhout<br />

Teleomorph: Filobasidiella bacillispora Kwon-Chung,<br />

Synonym: Cryptococcus neoformans var. gattii Vanbreus & Takashio<br />

Cryptococcus gattii has two serotypes (B and C) and has recently been reclassified as<br />

a separate species (Kwon-Chung et al. 2002). C. gattii generally has a more restricted<br />

geographical distribution than C. neoformans, causing human disease in climates<br />

ranging from temperate to tropical Australia, Papua New Guinea, parts of Africa, India,<br />

southeast Asia, Mexico, Brazil, Paraguay and Southern California, although recent<br />

infections have also been reported from Vancouver Island, Canada. Non-immunocompromised<br />

hosts are usually affected and large mass lesions in the lung and/or brain<br />

(cryptococcomas) are often present (Sorrell, 2001).<br />

Canavanine glycine bromothymol blue (CGB) agar (Kwon-Chung et al. 1982) is the<br />

media of choice to differentiate C. gattii from C. neoformans. This simple biotype test<br />

is based on the ability of C. gattii isolates to grow in the presence of L-canavanine and<br />

to assimilate glycine as a sole carbon source.<br />

C. gattii turns CGB agar blue within 2-5 days;<br />

C. neoformans does not grow on this medium<br />

Culture: Colonies (SDA) cream-coloured smooth, mucoid yeast-like colonies.<br />

Microscopy: Globose to ovoid budding yeast-like cells 3.0-7.0 x 3.3- 7.9 µm.<br />

India Ink Preparation: Positive - Distinct, wide gelatinous capsules are present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Budding yeast cells only.<br />

No pseudohyphae present.<br />

Bird Seed Agar: Colonies turn dark brown in colour as they selectively absorb a<br />

brown pigment from this media. Colonies are often more mucoid when compared to<br />

C. neoformans (Staib, 1987).<br />

Canavanine-Glycine-Bromothymol Blue (CGB) Agar: turns blue within 2-5 days.<br />

Key Features: encapsulated yeast; absence of pseudohyphae; growth at 37 O C; positive<br />

hydrolysis of urea; negative fermentation of sugars and positive assimilation of<br />

glucose, maltose, sucrose, galactose, trehalose, raffinose, inositol, cellobiose, rhamnose,<br />

arabinose, melezitose and xylose, and negative assimilation of nitrate, lactose,<br />

melibiose, erythritol and soluble starch; growth on bird seed (Guizotia abyssinica seed)<br />

or caffeic acid agar - colonies turn a dark brown colour; growth on CGB agar turning it<br />

blue within 2-5 days. RG-2 organism, however mating experiments for the production<br />

of basidiospores should be done in an appropriate pathogen handling cabinet.


Descriptions of Medical Fungi 53<br />

Cryptococcus gattii (Vanbreus. & Takashio) Kwon-Chung & Boekhout<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose +,w D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose + α-M-D-glucoside +<br />

Glucose - Maltose + D-Ribose v D-Gluconate +<br />

Galactose - Cellobiose +,w L-Rhamnose + DL-Lactate -<br />

Sucrose - Trehalose + D-Glucosamine v myo-Inositol +<br />

Maltose - Lactose - N-A-D-glucosamine v 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol - D-Glucuronate +<br />

Trehalose - Raffinose +,w Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol v Urease +<br />

Glucose + Soluble Starch + Galactitol + 0.1% Cycloheximide -<br />

Galactose + D-Xylose + D-Mannitol + Growth at 37 O C +<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 1->64 16 Amphotericin B 0.03-2 0.25<br />

Itraconazole


54<br />

Descriptions of Medical Fungi<br />

Cryptococcus neoformans (Sanfelice) Vuillemin<br />

Culture: Colonies (SDA) cream-coloured smooth, mucoid yeast-like colonies.<br />

Microscopy: Globose to ovoid budding yeast-like cells 3.0-7.0 x 3.3- 7.9 µm.<br />

India Ink Preparation: Positive - Distinct, wide gelatinous capsules are present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Budding yeast cells only.<br />

No pseudohyphae present.<br />

Bird Seed Agar: Colonies turn dark brown in colour as colonies selectively absorb a<br />

brown pigment from this media (Staib, 1987).<br />

Canavanine-Glycine-Bromothymol Blue (CGB) Agar: leaves this medium unchanged.<br />

Creatinine dextrose bromothymol blue thymine (CDBT) agar: Cryptococcus neoformans<br />

var. neoformans grows as bright red colonies, turning the medium a bright<br />

orange after 5 days. No colour change is observed for C. neoformans var. grubii.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose +,w D-Glucitol +<br />

Fermentation Sucrose + D-Arabinose + α-M-D-glucoside +<br />

Glucose - Maltose + D-Ribose v D-Gluconate +<br />

Galactose - Cellobiose +,w L-Rhamnose + DL-Lactate -<br />

Sucrose - Trehalose + D-Glucosamine v myo-Inositol +<br />

Maltose - Lactose - N-A-D-glucosamine v 2-K-D-gluconate +<br />

Lactose - Melibiose - Glycerol - D-Glucuronate +<br />

Trehalose - Raffinose +,w Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol v Urease +<br />

Glucose + Soluble Starch + Galactitol + 0.1% Cycloheximide -<br />

Galactose + D-Xylose + D-Mannitol + Growth at 37 O C +<br />

Key Features: encapsulated yeast; absence of pseudohyphae; growth at 37 O C; positive<br />

hydrolysis of urea; negative fermentation of sugars and positive assimilation of<br />

glucose, maltose, sucrose, galactose, trehalose, raffinose, inositol, cellobiose, rhamnose,<br />

arabinose, melezitose and xylose, and negative assimilation of nitrate, lactose,<br />

melibiose, erythritol and soluble starch; growth on bird seed (Guizotia abyssinica seed)<br />

or caffeic acid agar - colonies turn a dark brown colour; does not growth on CGB agar<br />

(no colour change). RG-2 organism, however mating experiments for the production<br />

of basidiospores should be done in an appropriate pathogen handling cabinet.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 1->64 8 Amphotericin B 0.03-2 0.5<br />

Itraconazole


Descriptions of Medical Fungi 55<br />

Cunninghamella bertholletiae Stadel<br />

Synonyms: Cunninghamella elegans Lendner<br />

Cunninghamella echinulata var. elegans (Lendner) Lunn & Shipton<br />

The genus Cunninghamella is characterised by white to grey, rapidly growing colonies,<br />

producing erect, straight, branching sporangiophores. These sporangiosphores<br />

end in globose or pyriform-shaped vesicles from which several one-celled, globose to<br />

ovoid, echinulate or smooth-walled sporangiola develop on swollen denticles. Chlamydospores<br />

and zygospores may also be present.<br />

Colonies are very fast growing, white at first, but becoming rather dark grey and powdery<br />

with sporangiola development. Sporangiophores to 20 μm wide, straight, with<br />

verticillate or solitary branches. Vesicles subglobose to pyriform, the terminal ones up<br />

to 40 µm and the lateral ones 10-30 µm in diameter. Sporangiola are globose (7-11<br />

µm diameter), or ellipsoidal (9-13 x 6-10 μm), verrucose or short-echinulate, hyaline<br />

singly but brownish in mass. Temperature: optimum 25 to 30 O C: maximum up to 50 O C.<br />

RG-2 organism.<br />

Cunninghamella species are mainly soil fungi of the Mediterranean and subtropical<br />

zones; they are only rarely isolated in temperate regions. The genus now contains<br />

seven species with C. bertholletiae the only known species to cause disease in man<br />

and animals which is often associated with trauma and immunosuppression.<br />

Key Features: zygomycete, clinical isolates grow at 40 O C, one-celled, globose to<br />

ovoid, echinulate sporangiola borne on swollen terminal or lateral globose to clavate<br />

fertile vesicles.<br />

Once again, there has been some confusion as to the correct name of this zygomycete.<br />

Many medical mycologists (McGinnis, 1980, Weitzman, 1984, and Rippon, 1988)<br />

preferred the name Cunninghamella bertholletiae because of the thermophilic nature<br />

of human isolates that grow at temperatures as high as 45 O C. However, Samson<br />

(1969) and Domsch et al. (1980) preferred the name Cunninghamella elegans and<br />

Lunn and Shipton (1983) went further and reduced C. elegans (= C. bertholletiae) to<br />

a variety of Cunninghamella echinulata; i.e. C. echinulata var. elegans. However, C.<br />

bertholletiae is currently the most acceptable name; C. elegans differs by having purely<br />

grey colonies and by not growing at temperatures above 40 O C (Weitzman and Crist,<br />

1979 and de Hoog et al. 2000).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range MIC Range MIC 90 90<br />

Fluconazole >64 >64 Amphotericin B 0.125-8 2<br />

Itraconazole 0.125-4 2 Flucytosine >256 >256<br />

Posaconazole 0.003-1 1 Voriconazole 8->64 >64<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Sun et al. (2002), Dannaoui et al. (2003), Espinel-Ingroff (2001, 2003), Singh et al.<br />

(2005), Sabatelli et al. (2006) and WCH in-house data.


56<br />

Descriptions of Medical Fungi<br />

10 μm<br />

Cunninghamella bertholletiae Stadel<br />

10 μm<br />

Microscopic morphology of Cunninghamella bertholletiae showing simple sporangiophores<br />

forming a swollen, terminal vesicle around which single-celled, globose<br />

to ovoid sporangiola develop on swollen denticles.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Weitzman (1984), Lunn and Shipton (1983), Domsch et al. (1980), Samson<br />

(1969), de Hoog et al (2000) and Ellis (2005b).


Descriptions of Medical Fungi 57<br />

Teleomorph: Cochliobolus Drechsler<br />

Curvularia Boedijn<br />

Colonies are fast growing, suede-like to downy, brown to blackish brown with a black<br />

reverse. Conidia are pale brown, with three or more transverse septa (phragmoconidia)<br />

and are formed apically through a pore (poroconidia) in a sympodially elongating<br />

geniculate conidiophore similar to Drechslera. Conidia are cylindrical or slightly<br />

curved, with one of the central cells being larger and darker, germination is bipolar and<br />

some species may have a prominent hilum.<br />

The genus Curvularia contains some 35 species which are mostly subtropical and<br />

tropical plant parasites; however three ubiquitous species, C. lunata, C. pallescens<br />

and C. geniculata have been recovered from human infections, principally from cases<br />

of mycotic keratitis. However, cases of subcutaneous, sinusitis, endocarditis, peritonitis<br />

and disseminated infection have also been reported in immunosuppressed patients.<br />

RG-1 organisms.<br />

Key Features: dematiaceous hyphomycete producing sympodial, pale brown,<br />

cylindrical or slightly curved phragmoconidia, with one of the central cells being larger<br />

and darker.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971),<br />

Domsch et al. (1980), McGinnis (1980), Rippon (1988) and de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

Conidia of Curvularia lunata.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-16 Itraconazole 0.03-32 Voriconazole 0.06-1<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001) and WCH in-house data.


58<br />

Descriptions of Medical Fungi<br />

Teleomorph: Nectria (Fries) Fr.<br />

Cylindrocarpon Wollenw.<br />

Colonies are fast growing, hyaline or bright-coloured, suede-like or woolly. Sporodochia<br />

may occasionally be present. Conidiophores consist of simple or repeatedly verticillate<br />

phialides, arranged in brush-like structures. Phialides are cylindrical to subulate,<br />

with small collarettes producing hyaline, smooth-walled conidia, which are arranged in<br />

slimy masses. Two types of conidia may be produced; macroconidia which are one to<br />

several septate, hyaline, straight or curved, cylindrical to fusiform, with a rounded apex<br />

and flat base; and microconidia which are one-celled, which are usually clearly distinct<br />

from the macroconidia. Chlamydospores may be present or absent, hyaline to brown,<br />

spherical, formed singly, in chains or in clumps, intercalary or terminal. RG-2 organism<br />

if isolated from humans.<br />

The genus contains 35 species, is widespread, isolated mostly from soil and is recorded<br />

as an occasional human and animal pathogen. Cylindrocarpon differs from<br />

Fusarium by lacking an asymmetrical foot-cell on the macroconidia.<br />

For descriptions of species, keys to taxa and additional information see Booth (1966),<br />

Domsch et al. (1980) and de Hoog et al. (2000).<br />

15 µm<br />

15 µm<br />

Culture, chlamydospores and macroconidia of Cylindrocarpon lichenicola.


Descriptions of Medical Fungi 59<br />

Teleomorph: Pyrenophora Fries<br />

Drechslera Ito<br />

Colonies are fast growing, suede-like to downy, brown to blackish brown with a black<br />

reverse. Conidia are pale to dark brown, usually cylindrical or subcylindrical, straight,<br />

smooth-walled, and are formed apically through a pore (poroconidia) on a sympodially<br />

elongating, geniculate conidiophore. Conidia are transversely septate (phragmoconidia),<br />

with the septum delimiting the basal cell formed first during conidium maturation.<br />

Germinating is from any or all cells and the hilum is not protuberant. RG-1 organism.<br />

McGinnis et al. (1986b) have reviewed the isolates from human and animal disease<br />

purported to be Drechslera or Helminthosporium and concluded that all pathogenic<br />

isolates examined actually belong to the genera Bipolaris or Exserohilum.<br />

Key Features: dematiaceous hyphomycete producing sympodial, pale brown,<br />

cylindrical or subcylindrical, transversely septate poroconidia.<br />

For descriptions of species, keys to taxa and additional information see Luttrell (1978),<br />

Ellis (1971 and 1976), Domsch et al. (1980), McGinnis (1980), McGinnis et al. (1986b),<br />

Sivanesan (1987), Rippon (1988) and de Hoog et al. (2000). Also see Descriptions for<br />

Bipolaris, Curvularia and Exserohilum.<br />

Antifungal<br />

Conidia of Drechslera.<br />

20 µm<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.25 Itraconazole 0.25 Voriconazole 0.06<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998).


60<br />

Descriptions of Medical Fungi<br />

Epicoccum purpurascens Ehrenb. ex Schlecht.<br />

Synonym: Epicoccum nigrum Link<br />

Colonies are fast growing, suede-like to downy, with a strong yellow to orange-brown<br />

diffusible pigment. When sporulating numerous black sporodochia (aggregates of<br />

conidiophores) are visible. Conidia are formed singly on densely compacted, nonspecialised,<br />

determinant, slightly pigmented conidiophores. Conidia are globose to<br />

pyriform, mostly l5-25 µm diameter with a funnel-shaped base and broad attachment<br />

scar, often seceding with a protuberant basal cell; i.e. aleuric or rhexolytic dehiscence<br />

of conidia. Conidia become multicellular (dictyoconidia), darkly pigmented and have a<br />

verrucose external surface. RG-1 organism.<br />

Epicoccum purpurascens is a cosmopolitan saprophyte of world-wide distribution which<br />

is occasionally isolated as a contaminant from clinical specimens like skin.<br />

Key Features: dematiaceous hyphomycete producing darkly pigmented, large globose<br />

to pyriform, verrucose dictyoconidia on a sporodochium.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971),<br />

Domsch et al. (1980), McGinnis (1980) and Samson et al. (1995).<br />

15 µm<br />

Conidia of Epicoccum purpurascens.


Descriptions of Medical Fungi 61<br />

Epidermophyton floccosum (Harz) Langeron et Milochevitch<br />

Colonies (SDA) are usually slow growing, greenish-brown or khaki-coloured with a<br />

suede-like surface, raised and folded in the centre, with a flat periphery and submerged<br />

fringe of growth. Older cultures may develop white pleomorphic tufts of mycelium. A<br />

deep yellowish-brown reverse pigment is usually present. Microscopic morphology<br />

shows characteristic smooth, thin-walled macroconidia which are often produced in<br />

clusters growing directly from the hyphae. Numerous chlamydospores are formed in<br />

older cultures. Microconidia are not formed.<br />

Epidermophyton floccosum is an anthropophilic dermatophyte with a world-wide distribution<br />

which often causes tinea pedis, tinea cruris, tinea corporis and onychomycosis.<br />

It is not known to invade hair in vivo and no specific growth requirements have been<br />

reported. RG-2 organism.<br />

Key Features: culture characteristics, microscopic morphology and clinical disease.<br />

For descriptions of species, keys to taxa and additional information see Rebell and<br />

Taplin (1970), Mackenzie et al. (1987), Rippon (1988) and de Hoog et al. (2000).<br />

20 µm<br />

15 µm<br />

Culture, macroconidia and chlamydospores of E. floccosum.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Griseofulvin 0.06-2 1 Amphotericin B 0.03-0.5 0.25<br />

Itraconazole 0.01-8 0.125 Fluconazole 0.5->64 >64<br />

Terbinafine 0.01-1 0.06 Voriconazole 0.01-8 0.125<br />

Fernandez-Torres et al. (2001) and Sabatelli et al. (2006) and WCH in-house data.


62<br />

Descriptions of Medical Fungi<br />

Exophiala dermatitidis (Kano) de Hoog<br />

Synonym: Wangiella dermatitidis (Kano) McGinnis<br />

Colonies are slow growing, initially yeast-like and black, becoming suede-like, olivaceous<br />

grey with the development of aerial mycelium with age. The initial yeast-like<br />

phase is referred to as the Phaeococcomyces exophialae synanamorph, which is characterised<br />

by unicellular, ovoid to elliptical, budding yeast-like cells. The yeast-like cells<br />

are hyaline and thin-walled when young becoming darkly pigmented (dematiaceous)<br />

and thick-walled when mature. With the development of mycelium, flask-shaped to cylindrical<br />

annellides are produced. Conidia are hyaline to pale brown, one-celled, round<br />

to obovoid, 2.0-4.0 x 2.5-6.0 µm, smooth-walled and accumulate in slimy balls at the<br />

apices of the annellides or down their sides. Cultures grow at 42 O C.<br />

E. dermatitidis has been isolated from plant debris and soil and is a recognised causative<br />

agent of mycetoma and phaeohyphomycosis in humans. RG-2 organism.<br />

For descriptions of species, keys to taxa and additional information see de Hoog and<br />

Hermanides-Nijhof (1977), McGinnis (1980), Hohl et al. (1983), Nishimura and Miyaji<br />

(1983), Matsumoto et al. (1984), Dixon and Polak-Wyss (1991), de Hoog et al.<br />

(2000).<br />

Antifungal<br />

10 µm<br />

Annellides and conidia of Exophiala dermatitidis.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

Range MIC90 Itraconazole 0.03-2 0.5 Amphotericin B 0.03-2 0.5<br />

Voriconazole 0.06-0.5 0.25 Posaconazole 0.03-1 nd<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff (2001), Espinel-Ingroff et al. (2001),<br />

Pfaller et al. (2002a) and WCH in-house data (nd = not done).


Descriptions of Medical Fungi 63<br />

Exophiala jeanselmei Complex<br />

Synonyms: Phialophora jeanselmei (Langeron) Emmons<br />

E. jeanselmei has long been recognised as heterogeneous (de Hoog 1977). Recent<br />

molecular studies have redefined Exophiala jeanselmei and three additional species<br />

have been identified: E. oligosperma, E. nishimurae, and E. xenobiotica (Vitale and<br />

de Hoog, 2002 , de Hoog et al. 2003, 2006). These species are morphologically very<br />

similar and can best be distinguished by genetic analysis.<br />

Conidiogenous cells are predominantly annellidic and erect, multicellular conidiophores<br />

are absent. No growth at 40 O C.<br />

E. jeanselmei Mature conidiogenous cells rocket-shaped, slightly darker than<br />

the supporting hyphae, with regular tapering annellated zones.<br />

E. oligosperma Mature conidiogenous cells remain concolorous with supporting<br />

hyphae and may be intercalary and lateral, the latter being flask<br />

or rocket-shaped. Annellated zones have the appearance of inconspicuous<br />

flat scars. Chlamydospores are absent.<br />

E. nishimurae Similar morphology to E. oligosperma, however large chlamydospore-like<br />

cells are present.<br />

E. xenobiotica A segregant genotype of the E. jeanselmei complex with less<br />

melanised conidiogenous cells.<br />

Colonies are initially smooth, greenish-grey to black, mucoid and yeast-like, becoming<br />

raised and developing tufts of aerial mycelium with age, often becoming domeshaped<br />

and suede-like in texture. Reverse is olivaceous-black. Numerous ellipsoidal,<br />

yeast-like, budding cells are usually present, especially in young cultures. Scattered<br />

amongst these yeast-like cells are larger, inflated, subglobose to broadly ellipsoidal<br />

cells (germinating cells) which give rise to short torulose hyphae that gradually change<br />

into unswollen hyphae. Conidia are formed on lateral pegs either arising apically or laterally<br />

at right or acute angles from essentially undifferentiated hyphae or from strongly<br />

inflated detached conidia. Conidiogenous pegs are 1-3 µm long, slightly tapering and<br />

imperceptibly annellate. Conidia are hyaline, smooth, thin-walled, broadly ellipsoidal,<br />

3.2-4.4 x 1.2-2.2 µm, and with inconspicuous basal scars. Cultures grow at 37 O C but<br />

not at 40 O C. RG-2 organism.<br />

E. jeanselmei has a world-wide distribution and is a recognised causative agent of<br />

mycetoma and phaeohyphomycosis in humans.<br />

For descriptions of species, keys to taxa and additional information see de Hoog and<br />

Hermanides-Nijhof (1977), de Hoog (1977, 1985), McGinnis and Padhye (1977),<br />

McGinnis (1978, 1980), Domsch et al. (1980), Nishimura and Miyaji (1983), Matsumoto<br />

et al. (1987), Dixon and Polak-Wyss (1991) and de Hoog et al. (2000, 2003, 2006).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

Range MIC90 Itraconazole 0.03-2 0.5 Amphotericin B 0.03-4 0.5<br />

Voriconazole 0.06-2 0.5 Posaconazole 0.25-0.5 0.5<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001), Nucci et al. (2001) and<br />

WCH in-house data.


64<br />

Descriptions of Medical Fungi<br />

Exophiala jeanselmei/spinifera Complex<br />

5 µm<br />

15 µm<br />

5 µm<br />

Annellides, conidia and conidiogenous pegs (annellides) on yeast-like cells and<br />

torulose hyphae of Exophiala jeanselmei.<br />

10 µm<br />

Erect, multiseptate conidiophores that are darker than the supporting hyphae,<br />

with long annellated zones and conidia of Exophiala spinifera.


Descriptions of Medical Fungi 65<br />

Exophiala spinifera Complex<br />

Synonyms: Phialophora spinifera Nielsen & Conant<br />

Rhinocladiella spinifera (Nielsen & Conant) de Hoog<br />

Recent molecular studies have re-examined Exophiala spinifera and have recognised<br />

two species: E. spinifera and E. attenuata (Vitale and de Hoog, 2002). These two<br />

species are morphologically very similar and can best be distinguished by genetic<br />

analysis.<br />

Conidiogenous cells are predominately annellidic and erect, multicellular conidiophores<br />

that are darker than the supporting hyphae are present. No growth at 40 O C.<br />

E. spinifera Annellated zones are long with clearly visible, frilled annellations.<br />

E. attenuata Annellated zones are inconspicuous and degenerate.<br />

Colonies are initially mucoid and yeast-like, black, becoming raised and developing<br />

tufts of aerial mycelium with age, finally becoming suede-like to downy in texture. Reverse<br />

is olivaceous-black. Conidiophores are simple or branched, erect or sub-erect,<br />

spine-like with rather thick brown pigmented walls. Conidia are formed in basipetal succession<br />

on lateral pegs either arising apically or laterally at right or acute angles from<br />

the spine-like conidiophores or from undifferentiated hyphae. Conidiogenous pegs<br />

are 1-3 µm long, slightly tapering and imperceptibly annellate. Conidia are one-celled,<br />

subhyaline, smooth, thin-walled, subglobose to ellipsoidal, 1.0-2.9 x 1.8-2.5 µm, and<br />

aggregate in clusters at the tip of each annellide. Toruloid hyphae and yeast-like cells<br />

with secondary conidia are typically present. No growth at 40 O C. RG-2 organism.<br />

E. spinifera has a world-wide distribution and is a recognised causative agent of<br />

mycetoma and phaeohyphomycosis in humans.<br />

For descriptions of species, keys to taxa and additional information see de Hoog and<br />

Hermanides-Nijhof (1977), McGinnis and Padhye (1977), Domsch et al. (1980), McGinnis<br />

(1980), Nishimura and Miyaji (1983), de Hoog (1985), Matsumoto et al. (1987),<br />

Dixon and Polak-Wyss (1991) and de Hoog et al. (2000, 2003, 2006).<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-1 Itraconazole 0.03-1 Voriconazole 0.125-1<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001) and WCH in-house data.


66<br />

Descriptions of Medical Fungi<br />

Exserohilum Leonard and Suggs<br />

Colonies are grey to blackish-brown, suede-like to floccose in texture and have an olivaceous<br />

black reverse. Conidia are straight, curved or slightly bent, ellipsoidal to fusiform<br />

and are formed apically through a pore (poroconidia) on a sympodially elongating<br />

geniculate conidiophore. Conidia have a strongly protruding, truncate hilum and the<br />

septum above the hilum is usually thickened and dark, with the end cells often paler<br />

than other cells, walls often finely roughed. Conidial germination is bipolar.<br />

The genus Exserohilum may be differentiated from the closely related genera Bipolaris<br />

and Dreschlera by forming conidia with a strongly protruding truncate hilum (i.e.<br />

exserted hilum). The hilum is defined as “a scar on a conidium at the point of attachment<br />

to the conidiophore”. In Drechslera species, the hilum does not protrude; in Bipolaris<br />

species the hilum protrudes only slightly. Several species of Exserohilum have<br />

been reported as agents of phaeohyphomycosis, notably E. rostratum (= E. halodes),<br />

E. mcginnisii and E. longirostratum. RG-1 organisms.<br />

Key Features: dematiaceous hyphomycete producing sympodial, transverse septate,<br />

ellipsoidal to fusiform conidia with a strongly protruding, truncate hilum.<br />

For descriptions of species, keys to taxa and additional information see Domsch et<br />

al. (1980), Alcorn (1983), Adam et al. (1986), McGinnis et al. (1986b), Rippon (1988),<br />

Burges et al. (1987), Dixon and Polak-Wyss (1991) and de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

20 µm<br />

Conidiophores and conidia with distinctive hilum (arrow) of E. rostratum.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-2 Itraconazole 0.03-0.5 Voriconazole 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


Descriptions of Medical Fungi 67<br />

Fonsecaea pedrosoi/monophora Complex<br />

Morphologically the genus Fonsecaea is defined by the presence of indistinct melanised<br />

conidiophores with blunt, scattered denticles bearing conidia singly or in short<br />

chains that eventually become branched. de Hoog et al. (2004) revised the genus on<br />

the basis of ribosomal DNA internal transcribed spacer (ITS) sequence data recognising<br />

two species; F. pedrosoi and F. monophora. The previously described species F.<br />

compacta was found to be a morphological variant of F. pedrosoi. Morphological F.<br />

pedrosoi and F. monophora are very similar and can best be distinguished by genetic<br />

analysis. F. monophora on average has slightly longer conidial chains and slightly<br />

shorter denticles than F. pedrosoi. All strains grow at 37 O C but not at 40 O C. Both species<br />

are recognised etiologic agents of chromoblastomycosis. RG-2 organism.<br />

Colonies are slow growing, flat to heaped and folded, suede-like to downy, olivaceous<br />

to black with black reverse. Conidiogenous cells pale olivaceous, arranged in loosely<br />

branched systems, with prominent denticles. Conidia pale olivaceous, clavate to<br />

ellipsoidal, in short chains, subhyaline, smooth and thin-walled, 3.5-5 x 1.5-2 µm.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Dixon and Polak-Wyss (1991), de Hoog et al. (2000), de Hoog et al. (2004).<br />

Antifungal<br />

Conidiophores and conidia of Fonsecaea.<br />

10 µm<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

Range MIC90 Itraconazole 0.03-1 0.25 Amphotericin B 0.03-2 1<br />

Voriconazole 0.06-1 0.06 Posaconazole 0.06-1 nd<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003)<br />

and WCH in-house data (nd = not done).


68<br />

Descriptions of Medical Fungi<br />

Fusarium Link ex Fries<br />

Colonies are usually fast growing, pale or bright coloured (depending on the species)<br />

with or without a cottony aerial mycelium. The colour of the thallus varies from whitish<br />

to yellow, pink, red or purple shades. Species of Fusarium typically produce both macro-<br />

and microconidia from slender phialides. Macroconidia are hyaline, two- to severalcelled,<br />

fusiform to sickle-shaped, mostly with an elongated apical cell and pedicellate<br />

basal cell. Microconidia are one- or two-celled, hyaline, smaller than macroconidia,<br />

pyriform, fusiform to ovoid, straight or curved. Chlamydospores may be present or<br />

absent.<br />

Cultures of F. oxysporum showing purple pigmentation<br />

and F. subglutinans showing pink pigmentation.<br />

Identification of Fusarium species is often difficult due to the variability between isolates<br />

(e.g. in shape and size of conidia and colony colour) and because not all features<br />

required are always well developed (e.g. the absence of macroconidia in some isolates<br />

after subculture). The important characters used in the identification of Fusarium species<br />

are as follows. Note: sporulation may need to be induced in some isolates and a<br />

good slide culture is essential.<br />

1. Colony growth diameters on potato dextrose agar and/or potato sucrose agar after<br />

incubation in the dark for 4 days at 25 O C.<br />

2. Culture pigmentation on potato dextrose agar and/or potato sucrose agar after incubation<br />

for 10-14 days with daily exposure to light.<br />

3. Microscopic morphology including shape of the macroconidia; presence or absence<br />

of microconidia; shape and mode of formation of microconidia; nature of the conidiogenous<br />

cell bearing microconidia; and presence or absence of chlamydospores.<br />

Most Fusarium species are soil fungi and have a world-wide distribution. Some are<br />

plant pathogens, causing root and stem rot, vascular wilt or fruit rot. Several species,<br />

notably F. oxysporum, F. solani and F. moniliforme are recognised as being pathogenic<br />

to man and animals causing hyalohyphomycosis (especially in burn victims and<br />

bone marrow transplant patients), mycotic keratitis and onychomycosis. Other species<br />

cause storage rot and are important mycotoxin producers.<br />

For descriptions of species, keys to taxa and additional information see Booth (1971<br />

and 1977), Domsch et al. (1980), McGinnis (1980), Burgess and Liddell (1983), Rippon<br />

(1988), Samson et al. (1995) and de Hoog et al. (2000).


Descriptions of Medical Fungi 69<br />

15 µm<br />

Fusarium oxysporum Schlecht<br />

Colonies growing rapidly, 4.5 cm in 4 days, aerial mycelium white, becoming purple,<br />

with discrete orange sporodochia present in some strains; reverse hyaline to dark blue<br />

or dark purple. Conidiophores are short, single, lateral monophialides in the aerial<br />

mycelium, later arranged in densely branched clusters. Macroconidia are fusiform,<br />

slightly curved, pointed at the tip, mostly three septate, basal cells pedicellate, 23-54 x<br />

3-4.5 µm. Microconidia are abundant, never in chains, mostly non-septate, ellipsoidal<br />

to cylindrical, straight or often curved, 5-12 x 2.3 - 3.5 µm. Chlamydospores are terminal<br />

or intercalary, hyaline, smooth or rough-walled, 5-13 µm. In contrast to F. solani<br />

the phialides are short and mostly non-septate. RG-2 organism.<br />

Antifungal<br />

15 µm<br />

Microconidia on short phialides and macroconidia of F. oxysporum.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC<br />

Antifungal<br />

Range MIC 90 90<br />

Itraconazole 0.5->16 >8 Amphotericin B 0.25->16 1-2<br />

Voriconazole 0.25->8 1-2 Posaconazole 1->8 4<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2001, 2003), Diekema et al. (2003),<br />

Cuenca-Estrella et al. (2006), Sabatelli et al. (2006) and WCH in-house data.


70<br />

Descriptions of Medical Fungi<br />

Fusarium solani (Mart.) Sacc.<br />

Colonies growing rapidly, 4.5 cm in 4 days, aerial mycelium white to cream, becoming<br />

bluish-brown when sporodochia are present. Macroconidia are formed after 4-7 days<br />

from short multi-branched conidiophores which may form sporodochia. They are 3- to<br />

5- septate (usually 3- septate), fusiform, cylindrical, often moderately curved, with an<br />

indistinctly pedicellate foot cell and a short blunt apical cell, 28-42 x 4-6 µm. Microconidia<br />

are usually abundant, cylindrical to oval, one- to two-celled and formed from long<br />

lateral phialides, 8-16 x 2-4.5 µm. Chlamydospores are hyaline, globose, smooth to<br />

rough-walled, borne singly or in pairs on short lateral hyphal branches or intercalary,<br />

6-10 µm. RG-2 organism.<br />

Antifungal<br />

15 µm<br />

15 µm<br />

15 µm<br />

Microconidia on long phialides, macroconidia and chlamydospores of F. solani.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC<br />

Antifungal<br />

Range MIC 90 90<br />

Itraconazole 0.25->16 >8 Amphotericin B 0.25->16 4<br />

Voriconazole 0.125->8 4 (>8) Posaconazole >8 >8<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2001, 2003), Diekema et al. (2003),<br />

Cuenca-Estrella et al. (2006), Sabatelli et al. (2006) and WCH in-house data.


Descriptions of Medical Fungi 71<br />

Geotrichum Link<br />

Species of the genus Geotrichum typically produce chains of hyaline, smooth, onecelled,<br />

subglobose to cylindrical arthroconidia by the holoarthric fragmentation of undifferentiated<br />

hyphae. Conidia may also develop sympodially and chlamydospores and<br />

endoconidia may also be present. The arthroconidia, which are quite variable in size<br />

may germinate at one end giving the appearance of a bud. However, the latter develops<br />

into a septate mycelium. True blastoconidia production is not found in the genus.<br />

This characteristic distinguishes the genus Geotrichum from Trichosporon which usually<br />

does produce blastoconidia.<br />

The need to exercise care when identifying species of Geotrichum must be stressed,<br />

as this name has often been used erroneously to describe any hyaline hyphomycete<br />

producing arthroconidia (McGinnis, 1980). Geotrichum species may be differentiated<br />

from each other using physiological and biochemical tests similar to those used for the<br />

identification of yeasts (Gueho, 1979 and Buchta and Otcenasek, 1988).<br />

For descriptions of species, keys to taxa and additional information see Gueho (1979),<br />

Domsch et al. (1980), McGinnis (1980), Barnett et al. (1983), Buchta and Otcenasek<br />

(1988), Samson et al. (1995), Kurtzman and Fell (1998) and de Hoog et al. (2000).<br />

Arthroconidium formation in G. candidum. Hyphal elements are progressively<br />

compartmentalised by fragmentation of septa. Conidial secession is<br />

by the centripetal separation (schizolysis) of a so called double septum and<br />

concomitant rupture of the original outer hyphal wall layer.<br />

Antifungal<br />

15 µm<br />

15 µm<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.25-32 8-32 Amphotericin B 0.06-1.0 0.125<br />

Itraconazole 0.03->32 >32 Flucytosine 0.125-16 4<br />

Voriconazole 0.03-0.5 0.25<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Girmenia et al. (2003), Kucukates et al. (2005) and WCH in-house data.


72<br />

Descriptions of Medical Fungi<br />

Geotrichum candidum Link<br />

Teleomorph: Galactomyces geotrichum (Butler & Petersen) Redhead & Malloch<br />

Colonies are fast growing, flat, white to cream, dry and finely suede-like with no reverse<br />

pigment. Hyphae are hyaline, septate, branched and break up into chains of hyaline,<br />

smooth, one-celled, subglobose to cylindrical arthroconidia. They are 6-12 x 3-6 µm in<br />

size and are released by the separation of a double septum. RG-1 organism.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, n No data<br />

Germ Tube - L-Sorbose + L-Arabinose - D-Glucitol +<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose v Maltose - D-Ribose v D-Gluconate -<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate v<br />

Sucrose - Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine n 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol v Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide +<br />

Galactose + D-Xylose + D-Mannitol v Growth at 37 O C v<br />

Geotrichum candidum is an extremely common fungus with a world-wide distribution.<br />

Pulmonary involvement is the most frequently reported form of the disease, but bronchial,<br />

oral, vaginal, cutaneous and alimentary infections have also been noted.<br />

Geotrichum capitatum (Diddens & Lodder) v. Arx<br />

Teleomorph: Dipodascus capitatis de Hoog et al.<br />

Synonyms: Trichosporon capitatum, Blastoschizomyces capitis<br />

Colonies are moderately fast growing, flat, whitish, and finely suede-like with no reverse<br />

pigment. Hyphae are profusely branched at acute angles, with terminal and intercalary<br />

conidiogenous cells which form long, cicatrized rachids on which conidia are borne.<br />

Conidia are hyaline, smooth, one-celled, cylindrical to clavate, with a rounded apex<br />

and flat base, 7-10 x 2.5-3.5 µm. Rectangular arthroconidia are also often present.<br />

RG-2 organism.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow, n No data<br />

Germ Tube - L-Sorbose v L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose - D-Arabinose - α-M-D-glucoside -<br />

Glucose - Maltose - D-Ribose v D-Gluconate -<br />

Galactose - Cellobiose - L-Rhamnose - DL-Lactate +<br />

Sucrose - Trehalose - D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine n 2-K-D-gluconate -<br />

Lactose - Melibiose - Glycerol + D-Glucuronate -<br />

Trehalose - Raffinose - Erythritol - Nitrate -<br />

Assimilation Melezitose - Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide +<br />

Galactose + D-Xylose - D-Mannitol - Growth at 40 O C +<br />

Geotrichum capitatum occurs quite commonly in humans, usually as a transient component<br />

of normal skin flora and sputum. Systemic infections including pulmonary,<br />

fungemia and endocarditis have been reported in immunosuppressed patients.


Descriptions of Medical Fungi 73<br />

Gliocladium Corda<br />

The genus Gliocladium is often described as a counterpart of Penicillium with slimy<br />

conidia. Colonies are fast growing, suede-like to downy in texture, white at first, sometimes<br />

pink to salmon, becoming pale to dark green with sporulation. The most characteristic<br />

feature of the genus is the distinctive erect, often densely penicillate conidiophores<br />

with phialides which bear slimy, one-celled hyaline to green, smooth-walled<br />

conidia in heads or columns. Although, some penicillate conidiophores are always<br />

present, Gliocladium species may also produce verticillate branching conidiophores<br />

which can be confused with Verticillium or Trichoderma.<br />

Gliocladium species have a world-wide distribution and are commonly isolated from a<br />

wide range of plant debris and soil. RG-1 organism.<br />

Key Features: hyphomycete producing distinctive erect penicillate conidiophores with<br />

phialides bearing clusters of single-celled conidia.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980), Onions et al. (1981), Rippon (1988), de Hoog et al. (2000).<br />

Conidiophore and conidia of Gliocladium.<br />

10 µm


74<br />

Descriptions of Medical Fungi<br />

Graphium Corda<br />

The genus Graphium is characterised by the formation of synnemata which consist of<br />

a more or less compact group of erect conidiophores that are cemented together, usually<br />

splaying out and bearing conidia at the apex. Synnemata are darkly pigmented,<br />

erect and occur solitary or in clusters. Conidia are hyaline, one-celled, smooth, subglobose<br />

to ovoid and are usually aggregated in slimy heads at the apex of the synnemata.<br />

Colonies are effuse, grey, olivaceous brown or black.<br />

Graphium eumorphum is one of the synanamorphs of Pseudallescheria boydii and is<br />

commonly found on woody plant material. RG-1 organism.<br />

Key Features: dematiaceous hyphomycete producing erect synnemata with apical<br />

aggregates of single-celled conidia in slimy heads.<br />

For descriptions of species, keys to taxa and additional information see Barron (1968),<br />

Ellis (1971), McGinnis (1980) and de Hoog et al. (2000).<br />

20 µm<br />

Synnemata and conidia of Graphium.


Descriptions of Medical Fungi 75<br />

Histoplasma capsulatum Darling<br />

Histoplasma capsulatum exhibits thermal dimorphism growing in living tissue or in culture<br />

at 37 O C as a budding yeast-like fungus and in soil or culture at temperatures below<br />

30 O C as a mould.<br />

Colonies (SDA) at 25 O C are slow growing, white or buff-brown, suede-like to cottony<br />

with a pale yellow-brown reverse. Other colony types are glabrous or verrucose, and a<br />

red pigmented strain has been noted (Rippon, 1988). Microscopic morphology shows<br />

the presence of characteristic large, rounded, single-celled, 8-14 µm in diameter, tuberculate<br />

macroconidia formed on short, hyaline, undifferentiated conidiophores. Small,<br />

round to pyriform, 2-4 µm in diameter, microconidia borne on short branches or directly<br />

on the sides of the hyphae may also be present.<br />

On brain heart infusion agar containing blood incubated at 37 O C colonies are smooth,<br />

moist, white and yeast-like. Microscopically, numerous small round to oval budding<br />

yeast-like cells, 3-4 x 2-3 µm in size are observed.<br />

Three varieties of Histoplasma capsulatum are recognised, depending on the clinical<br />

disease: var. capsulatum is the common cause of histoplasmosis; var. duboisii is the<br />

African type and var. farciminosum causes lymphangitis in horses. Histoplasma isolates<br />

may also resemble species of Sepedonium and Chrysosporium. Traditionally,<br />

positive identification required conversion of the mould form to the yeast phase by<br />

growth at 37 O C on enriched media, however culture identification by exoantigen test is<br />

now the method of choice.<br />

WARNING: RG-3 organism. Cultures of Histoplasma capsulatum represent a severe<br />

biohazard to laboratory personnel and must be handled with extreme caution in an<br />

appropriate pathogen handling cabinet.<br />

Key Features: clinical history, tissue morphology, culture morphology and positive<br />

exoantigen test.<br />

Histoplasma capsulatum has a world wide distribution, however the Mississippi-Ohio<br />

River Valley in the USA is recognised as a major endemic region. Environmental isolations<br />

of the fungus have been made from soil enriched with excreta from chicken, starlings<br />

and bats. Histoplasmosis is an intracellular mycotic infection of the reticuloendothelial<br />

system caused by the inhalation of the fungus. Approximately 95% of cases<br />

of histoplasmosis are inapparent, subclinical or benign. Five percent of the cases have<br />

chronic progressive lung disease, chronic cutaneous or systemic disease or an acute<br />

fulminating fatal systemic disease. All stages of this disease may mimic tuberculosis.<br />

Sporadic cases do occur in Australia.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Chandler et al. (1980), George and Penn (1986), Rippon (1988) and de Hoog<br />

et al. (2000).


76<br />

Descriptions of Medical Fungi<br />

20 µm<br />

Culture and microscopic morphology of the saprophytic or mycelial form of<br />

H. capsulatum showing characteristic large, rounded, single-celled, tuberculate<br />

macroconidia formed on short, hyaline, undifferentiated conidiophores.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.03-2 0.5-1 Posaconazole 0.25-1 0.25 (2)<br />

Fluconazole 0.125-64 16 Voriconazole 0.03-2 0.25 (1)<br />

Itraconazole 0.03-8 0.06 (1)<br />

Histoplasma capsulatum Darling<br />

Limited data available. Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003), Gonzales<br />

et al. (2005) and Sabatelli et al. (2006).


Descriptions of Medical Fungi 77<br />

Synonyms: Phaeoannellomyces werneckii (Horta) McGinnis & Schell<br />

Exophiala werneckii (Horta) v. Arx<br />

Colonies are slow growing, initially mucoid, yeast-like and shiny black. However with<br />

age they develop abundant aerial mycelia and become dark olivaceous in colour. Microscopically,<br />

colonies consist of brown to dark olivaceous, septate hyphal elements<br />

and numerous two-celled, pale brown, cylindrical to spindle-shaped yeast-like cells that<br />

taper towards the ends to form an annellide. Most yeast-like cells also have prominent<br />

darkly-pigmented septa. Annellides may also arise from the hyphae. Conidia are one<br />

to two-celled, cylindrical to spindle-shaped, hyaline to pale brown and usually occur in<br />

aggregated masses. RG-1 organism.<br />

Hortaea werneckii is a common saprophytic fungus believed to occur in soil, compost,<br />

humus and on wood in humid tropical and sub-tropical regions and is the causative<br />

agent of tinea nigra in humans.<br />

Key Features: dematiaceous hyphomycete, two-celled yeast-like cells producing<br />

annelloconidia.<br />

For description of species, keys to taxa and additional information see Mok (1982),<br />

McGinnis (1980), McGinnis et al. (1985), Rippon (1988) and de Hoog et al. (2000).<br />

Antifungal<br />

Hortaea werneckii (Horta) Nishimura & Miyaji<br />

Culture and conidia of Hortaea werneckii.<br />

20 µm<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-1 Itraconazole 0.03-0.25 Voriconazole 0.03-0.125<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


78<br />

Descriptions of Medical Fungi<br />

Lasiodiplodia theobromae (Pat.) Griffon & Maublanc<br />

Teleomorph: Botryosphaeria rhodina (Berk, & Curt. v. Arx<br />

Synonym: Botryodiplodia theobromae Patouillard<br />

Colonies are greyish sepia to mouse grey to black, fluffy with abundant aerial mycelium;<br />

reverse fuscous black to black. Pycnidia are simple or compound, often aggregated,<br />

stromatic, ostiolate, frequently setose, up to 5 mm wide. Conidiophores are hyaline,<br />

simple, sometimes septate, rarely branched cylindrical, arising from the inner layers of<br />

cells lining the pycnidial cavity. Conidiogenous cells are hyaline, simple, cylindrical to<br />

subobpyriform, holoblastic, annellidic. Conidia are initially unicellular, hyaline, granulose,<br />

subovoid to ellipsoide-oblong, thick-walled, base truncate; mature conidia oneseptate,<br />

cinnamon to fawn, often longitudinally striate, 20-30 x 10-15 µm. Paraphyses<br />

when present are hyaline, cylindrical, sometimes septate, up to 50 µm long.<br />

Lasiodiplodia theobromae is a well known plant pathogen and it has been reported<br />

from about 500 host plants, mainly confined to an area 40 O north to 40 O south of the<br />

equator. It has also been associated with mycotic keratitis, lesions on nail and subcutaneous<br />

tissue. RG-1 organism.<br />

Key Features: coelomycete, with pycnidia producing characteristic two-celled, dark<br />

brown, striated conidia.<br />

For description of species, keys to taxa and additional information see de Hoog et al.<br />

(2000).<br />

10 µm<br />

Mature two-celled dark brown conidia with typical striations of L. theobromae.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03 Itraconazole 16 Voriconazole 0.25<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

WCH in-house data only.


Descriptions of Medical Fungi 79<br />

Lecythophora Nannfeldt<br />

Colonies are pink to salmon, later becoming blackish, smooth, often mucoid or yeastlike.<br />

Conidiogenous cells are poorly differentiated, usually lateral or intercalary, hyphae<br />

bearing one or several scattered inconspicuous collarettes, either sessile or on small<br />

outgrowths. Conidia are hyaline, smooth and thin walled, broadly ellipsoidal, cylindrical,<br />

reniform or allantoid. Chlamydospores may be present. Lecythophora contains 6<br />

species, with two species of medical interest; L hoffmannii and L. mutabilis.<br />

Lecythophora hoffmannii (J.F.H. Beyma) W. Gams & McGinnis<br />

Teleomorph: Coniochaeta ligniaria (Grev.) Cooke<br />

Colonies are flat, smooth, moist, pink to orange, with regular and sharp margin; reverse<br />

pink. Hyphae are narrow, hyaline, producing conidia laterally from small collarettes<br />

directly on the hyphae, or from lateral cells which are sometimes arranged in dense<br />

groups; lateral cells flask-shaped or nearly cylindrical. Collarettes are unpigmented,<br />

about 1.5 µm wide. Conidia are hyaline, smooth and thin walled, broadly ellipsoidal to<br />

cylindrical or allantoid, 3.0-3.5 x 1.5-2.5 µm, produced in slimy heads. RG-1 organism.<br />

For description of species, keys to taxa and additional information see de Hoog (1983)<br />

and de Hoog et al. (2000).<br />

10 µm<br />

10 µm<br />

Culture, hyphae with small collarettes and conidia of Lecythophora hoffmannii.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.06-0.5 Itraconazole 0.06-32 Voriconazole 0.125-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998).


80<br />

Descriptions of Medical Fungi<br />

Madurella grisea Mackinnon, Ferrada and Montemayer<br />

The genus Madurella is based on tissue morphology (mycetoma with black grains)<br />

and the formation of sterile cultures on mycological media. Both M. mycetomatis and<br />

M. grisea have been isolated from soil and are one of the major causative agents of<br />

mycetoma.<br />

Colonies are slow growing, dark, leathery, folded with radial grooves and with a light<br />

brown to greyish surface mycelium. With age, colonies become dark brown to reddish-brown<br />

and have a brownish-black reverse. Microscopically, cultures are sterile,<br />

although hyphae of two widths have been described, thin at 1-3 µm in width or broad at<br />

3-5 µm in width. The optimum temperature for growth of M. grisea is 30 O C; this fungus<br />

does not grow at 37 O C. RG-2 organism.<br />

M. grisea can be distinguished from Madurella mycetomatis by the inability to grow at<br />

37 O C and to assimilate lactose.<br />

Key Features: black grain mycetoma, no growth at 37 O C, no diffusible brown pigment<br />

produced on culture and absence of conidia.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Chandler et al. (1980), Rippon (1988) and de Hoog et al. (2000).<br />

Antifungal<br />

100 µm<br />

Grains of Madurella grisea (tissue microcolonies) are black, round to<br />

lobed, soft to firm, up to 1.0 mm, with two distinctive zones, a hyaline to<br />

weakly pigmented central zone and a deeply pigmented periphery.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.25 Itraconazole 0.5 Voriconazole 0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001).


Descriptions of Medical Fungi 81<br />

Madurella mycetomatis (Laveran) Brumpt<br />

Colonies are slow growing, flat and leathery at first, white to yellow to yellowish-brown,<br />

becoming brownish, folded and heaped with age and with the formation of aerial mycelia.<br />

A brown diffusible pigment is characteristically produced in primary cultures. Although<br />

most cultures are sterile, two types of conidiation have been observed, the first<br />

being flask-shaped phialides that bear rounded conidia, the second being simple or<br />

branched conidiophores bearing pyriform conidia (3-5 µm) with truncated bases. The<br />

optimum temperature for growth of this mould is 37 O C. RG-2 organism<br />

Grains of Madurella mycetomatis (tissue microcolonies) are brown or black, 0.5-1.0<br />

mm in size, round or lobed, hard and brittle, composed of hyphae which are 2-5 µm in<br />

diameter, with terminal cells expanded to 12-15 (30) µm in diameter.<br />

M. mycetomatis can be distinguished from Madurella grisea by growth at 37 O C and its<br />

inability to assimilate sucrose.<br />

Key Features: black grain mycetoma, growth at 37 O C, diffusible brown pigment<br />

produced on culture and the occasional presence of phialides.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Chandler et al. (1980), Rippon (1988) and de Hoog et al. (2000).<br />

20 µm<br />

Culture showing brown diffusible pigment and phialides of M. mycetomatis.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03 Itraconazole 0.03-0.125 Voriconazole 0.03-0.6<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and Espinel-Ingroff et al. (2001).


82<br />

Descriptions of Medical Fungi<br />

Malassezia Baillon<br />

Malassezia is characterised by globose, oblong-ellipsoidal to cylindrical, yeast cells.<br />

Reproduction is by budding on a broad base and from the same site at one pole<br />

(unipolar). With the exception of M. pachydermatis, Malassezia are lipophilic yeasts,<br />

therefore in vitro growth must be stimulated by natural oils or other fatty substances.<br />

The most common method used is to overlay Sabouraud’s dextrose agar containing<br />

cycloheximide (actidione) with olive oil or alternatively to use a more specialised media<br />

like Dixon’s agar which contains glycerol mono-oleate. On such media, colonies are<br />

cream to yellowish, smooth or lightly wrinkled, glistening or dull, and with the margin<br />

being either entire or lobate (see photo). Seven species have now been recognised<br />

(Gueho et al. 1996). RG-2 organisms.<br />

Species Source<br />

M. furfur humans, normal flora, pityriasis<br />

M. globosa humans, normal flora, pityriasis<br />

M. pachydermatis animals, especially dogs<br />

M. obtusa humans, normal flora,<br />

atopic dermatitis<br />

M. restricta humans, normal flora<br />

M. slooffiae human and pig normal flora<br />

M. sympodialis humans, normal flora<br />

Identification criteria for the differentiation of Malassezia species (de Hoog et. al. 2000).<br />

Buds SDA 40 O C Cremophor<br />

EL<br />

Tween<br />

80<br />

Tween<br />

40<br />

Tween<br />

20<br />

Esculine Catalase<br />

M. furfur wide - + + + + + w +<br />

M. globosa narrow - - - - - - - +<br />

M. pachydermatis wide + + -,w + + -,w v v<br />

M. obtusa wide - - - - - - + +<br />

M. restricta narrow - - - - - - - -<br />

M. slooffiae wide - + - +,w + + - +<br />

M. sympodialis narrow - + -,w + + + + +<br />

For descriptions of species, keys to taxa and additional information see Guillot and<br />

Gueho (1995), Gueho et al. (1996), Guillot et al. (1996, 2000), de Hoog et al. (2000).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125->64 4 (8) Amphotericin B 0.03-16 1 (8)<br />

Itraconazole 0.03-16 0.125 Voriconazole 0.03-16 0.125 (1)<br />

Ketoconazole 0.03-4 0.25 Posaconazole 0.03-32 0.125 (2)<br />

Very limited data available. Special growth conditions are needed for antifungal<br />

susceptibility testing. Nakamura et al. (2000), Velegraki et al. (2004) and Miranda et<br />

al. (2007).


Descriptions of Medical Fungi 83<br />

Malbranchea Saccardo<br />

Colonies are white to sulphur-yellow to ochre-brown in colour, suede-like in texture,<br />

with a reddish-brown reverse, and often a reddish diffusible pigment. Microscopic morphology<br />

shows typical hyaline, one-celled, cylindrical, truncate, alternate arthroconidia<br />

produced in terminal fertile portions of the hyphae. Arthroconidia are released by lysis<br />

of the disjunctor cells. These arthroconidia may be perceived as a yellow dust when<br />

released at maturity. RG-1 organisms.<br />

Key Features: hyphomycete producing alternate arthroconidia with disjunctor cells.<br />

Malbranchea species are soil fungi of world-wide distribution which microscopically<br />

may resemble Coccidioides immitis/posadasii. Exoantigen tests are now the method<br />

of choice for culture identification of C. immitis/posadasii.<br />

For description of the species, keys to taxa and additional information see Cooney and<br />

Emerson (1964), McGinnis (1980), Rippon (1988) and de Hoog et al. (2000).<br />

20 µm<br />

Arthroconidia of Malbranchea.


84<br />

Descriptions of Medical Fungi<br />

Microsporum Gruby<br />

Teleomorph: Arthroderma Currey and Berkeley emend Weitzman et al.<br />

Microsporum species form both macro- and microconidia on short conidiophores.<br />

Macroconidia are hyaline, multiseptate, variable in form, fusiform, spindle-shaped to<br />

obovate, ranging from 7-20 x 30-60 µm in size, with thin- or thick- echinulate to verrucose<br />

cell walls. Their shape, size and cell wall features are important characteristics<br />

for species identification. Microconidia are hyaline, single-celled, pyriform to clavate,<br />

smooth-walled, 2.5-3.5 x 4-7 µm in size and are not diagnostic for any one species.<br />

The separation of this genus from Trichophyton is essentially based on the roughness<br />

of the macroconidial cell wall, although in practice this may sometimes be difficult to<br />

observe. Seventeen species of Microsporum have been described (Rippon, 1988)<br />

however only the more common species are included in these descriptions.<br />

It is essential to observe macroconidia when identifying species of Microsporum.<br />

Strains of M. canis often do not produce macroconidia and/or microconidia on primary<br />

isolation media and it is recommended that sub-cultures be made onto polished rice<br />

grains to stimulate sporulation. These non-sporulating strains of M. canis are often<br />

erroneously identified as M. audouinii and it is surprising just how many laboratories<br />

have difficulty in differentiating between M. canis and M. audouinii.<br />

For descriptions of species, keys to taxa and additional information see Rebell and<br />

Taplin (1970), Vanbreusegham et al. (1978), Rippon (1988), McGinnis (1980), Domsch<br />

et al. (1980), Ajello (1977), Weitzman et al. (1986), Mackenzie et al. (1986), Kane et al.<br />

(1997) and de Hoog et al. (2000).<br />

a<br />

(a) M. audouinii showing poor growth on rice grains, usually being visible only<br />

as a brown discolouration. (b) M. canis on rice grains showing good growth,<br />

yellow pigmentation and sporulation.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Griseofulvin 0.125-2 1 Amphotericin B 0.03-8 1-2<br />

Itraconazole 0.01-4 0.25-0.5 Fluconazole 0.06->64 64<br />

Terbinafine 0.01-16 0.06 Voriconazole 0.007-1 0.5<br />

Fernandez-Torres et al. (2001), Sabatelli et al. (2006) and WCH in-house data.<br />

b


Descriptions of Medical Fungi 85<br />

Microsporum audouinii Gruby<br />

Colonies (SDA) are flat, spreading, greyish-white to light tan-white in colour, and have<br />

a dense suede-like to downy surface, suggestive of mouse fur in texture. Reverse<br />

can be yellow-brown to reddish-brown in colour. Some strains may show no reverse<br />

pigment. Macroconidia and microconidia are only rarely produced, most cultures are<br />

sterile or produce only occasional thick-walled terminal or intercalary chlamydospores.<br />

When present macroconidia may resemble those of M. canis but are usually longer,<br />

smoother and more irregularly fusiform in shape; microconidia when present are pyriform<br />

to clavate in shape and are similar to those seen in other species of Microsporum.<br />

So called pectinate (comb-like) hyphae and racquet hyphae (a series of hyphal segments<br />

swollen at one end) may also be present. RG-2 organism.<br />

Culture and a thick-walled intercalary chlamydospore of M. audouinii. Note:<br />

macroconidia and microconidia are only rarely produced.<br />

Growth on Rice Grains: Very poor or absent, usually being visible only as a brown<br />

discolouration. This is one of the features which distinguish M. audouinii from M.<br />

canis.<br />

Reverse Pigment on Potato Dextrose Agar: Salmon to pinkish-brown (M. canis is<br />

bright yellow).<br />

Lactritmel Agar: Colonies are usually flat, spreading, with a fine, whitish suede-like<br />

surface and a very pale yellow-brown reverse. Microscopic morphology as described<br />

above.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. Cultures are flat, white, suede-like to downy, with a yellowbrown<br />

reverse. Note: growth of some strains of M. audouinii is enhanced by the presence<br />

of thiamine (Trichophyton agar No.4).<br />

Hair Perforation Test: Negative after 28 days.<br />

10 µm<br />

Key Features: absence of conidia, poor or no growth on polished rice grains, inability<br />

to perforate hair in vitro, and culture characteristics.<br />

M. audouinii is an anthropophilic fungus causing non-inflammatory infections of scalp<br />

and skin especially in children. Once the cause of epidemics of tinea capitis in Europe<br />

and North America, it is now becoming less frequent. Invaded hairs show an ectothrix<br />

infection and usually fluoresce a bright greenish-yellow under Wood’s ultra-violet light.<br />

Only rarely found in Australasia, most reports are in fact non-sporulating strains of M.<br />

canis.


86<br />

Descriptions of Medical Fungi<br />

Microsporum canis Bodin<br />

Teleomorph: Arthroderma otae (Hasegawa and Usui) McGinnis, et al.<br />

Colonies (SDA) are flat, spreading, white to cream-coloured, with a dense cottony<br />

surface which may show some radial grooves. Colonies usually have a bright golden<br />

yellow to brownish yellow reverse pigment, but non-pigmented strains may also occur.<br />

Macroconidia are typically spindle-shaped with 5-15 cells, verrucose, thick-walled and<br />

often have a terminal knob, 35-110 x 12-25 µm. A few pyriform to clavate microconidia<br />

are also present. Macroconidia and/or microconidia are often not produced on primary<br />

isolation media and it is recommended that sub-cultures be made onto Lactritmel Agar<br />

and/or boiled polished rice grains to stimulate sporulation. RG-2 organism.<br />

Growth on Rice Grains: good growth of white aerial mycelium with production of yellow<br />

pigment. Microscopy reveals numerous macroconidia and microconidia similar to<br />

those described above.<br />

Lactritmel Agar: Flat, white suede-like to cottony colony with a bright yellow reverse.<br />

Microscopy reveals moderate numbers of thick-walled, multiseptate, long, spindleshaped<br />

macroconidia, some of which show a terminal knob. Walls of macroconidia<br />

are slightly rough or echinulate especially at terminal knobs. Numerous clavate to<br />

pyriform microconidia are also present in this strain. Lactritmel agar with sterile soil<br />

added is also an excellent medium for the stimulation of macroconidial development<br />

in M. canis.<br />

Reverse Pigment on Potato Dextrose Agar: Bright yellow (both M. audouinii and M.<br />

canis var. equinum are salmon to pinkish-brown).<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. Cultures are flat, white, suede-like to downy, with a yellow to<br />

pale yellow-brown reverse.<br />

Hair Perforation Test: Positive at 14 days.<br />

Key Features: distinctive macroconidia and culture characteristics. Abundant growth<br />

and sporulation on polished rice grains and in vitro perforation of hair.<br />

Culture of Microsporum canis.


Descriptions of Medical Fungi 87<br />

Microsporum canis Bodin<br />

Typical spindle-shaped macroconidia of Microsporum canis.<br />

20 µm<br />

Dysgonic strains of M. canis are rare but may also occur. These dysgonic strains have<br />

a typically heaped and folded, yellow-brown thallus and macroconidia are usually<br />

absent. However, typical colonies and macroconidia of M. canis are usually produced<br />

by this variant when subcultured onto polished rice grains. Note: the dysgonic type<br />

colony of M. canis is similar to that of Microsporum ferrugineum.<br />

M. canis is a zoophilic dermatophyte of world-wide distribution and is a frequent cause<br />

of ringworm in humans, especially children. Invades hair, skin and rarely nails. Cats<br />

and dogs are the main sources of infection. Invaded hairs show an ectothrix infection<br />

and fluoresce a bright greenish-yellow under Wood’s ultra-violet light.


88<br />

Descriptions of Medical Fungi<br />

Microsporum canis var. distortum di Menna & Marples<br />

Supplementary description for Microsporum canis var. distortum, a dysgonic variant of<br />

M. canis with distinctive distorted macroconidia. Abundant growth and sporulation on<br />

rice grains. RG-2 organism.<br />

Microsporum canis var. distortum is a zoophilic fungus known to cause infections in<br />

cats, dogs and other animals. It is a rare cause of tinea capitis in New Zealand,<br />

Australia and North America. Clinical disease is similar to M. canis . Invaded hairs<br />

show an ectothrix infection and fluoresce a bright greenish-yellow under Wood’s ultraviolet<br />

light.<br />

20 µm<br />

Culture and distorted macroconidia of M. canis var. distortum.


Descriptions of Medical Fungi 89<br />

Microsporum canis var. equinum (Delacroix & Bodin) comb. nov.<br />

Basionym: Microsporum equinum (Delacroix & Bodin) Gueguen<br />

Microsporum equinum is now considered to be a genotypic synonym of Microsporum<br />

canis (de Hoog et al. 2000), however we propose it be maintained as a variety of M.<br />

canis due to phenotypic and epidemiologic differences.<br />

Colonies are flat, spreading, suede-like, pale buff to pale salmon, usually with some radial<br />

furrows. A buff to pinkish-buff to yellow-brown reverse pigment is produced. Note:<br />

only a few strains produce conidia on primary isolation, however growth on urea agar<br />

usually stimulates the production of macroconidia. Macroconidia are small (especially<br />

when compared to those produced by M. canis), broad, irregular, spindle-shaped, 18-<br />

60 x 5-15 mm with rough thick walls and few septa. Microconidia are pyriform to clavate<br />

in shape, 3-9 x 1.5-3.5 mm, but are rarely produced. RG-2 organism.<br />

Growth on Rice Grains: Poor with minimal surface growth, usually being visible only<br />

as a brown discolouration. This is one of the features which distinguish M. canis var.<br />

equinum from M. canis.<br />

Reverse Pigment on Potato Dextrose Agar: Salmon to pinkish-brown (M. canis is<br />

bright yellow).<br />

Lactritmel Agar: Colonies are usually flat, spreading, with a fine, whitish suede-like<br />

surface and a very pale yellow-brown reverse. Microscopic morphology as described<br />

above.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. Cultures are flat, white, suede-like to downy, with a yellowbrown<br />

reverse.<br />

Hair Perforation Test: Negative after 28 days.<br />

Key Features: macroconidial shape and size, inability to perforate hair in vitro, and<br />

poor growth on polished rice grains.<br />

20 µm<br />

Culture and macroconidia of M. canis var. equinum.<br />

Microsporum equinum is a<br />

rare cause of ringworm of<br />

horses. Invaded hairs show<br />

an ectothrix infection and<br />

fluoresce a bright greenishyellow<br />

under Wood’s ultraviolet<br />

light. Rarely infects<br />

man or other animal species.<br />

Reported from Australia,<br />

Europe and North America.


90<br />

Descriptions of Medical Fungi<br />

Teleomorph: Arthroderma cajetani Ajello, Weitzman, McGinnis & Padhye<br />

Colonies (SDA) are flat, spreading, buff to pale brown, powdery to suede-like, with a<br />

slightly raised and folded centre and some radial grooves. Reverse pigment dark reddish<br />

brown. Numerous large, very thick-walled, echinulate (rough) elliptical macroconidia<br />

with predominantly 5-6 septa but may be 2-8 septate. Occasional spirals may be<br />

seen. Moderate numbers of mainly slender clavate with some pyriform microconidia<br />

are present. The macroconidia are quite characteristic and diagnostic of M. cookei and<br />

further tests are not necessary. The thick walls and usually larger size of the macroconidia<br />

distinguish M. cookei from M. gypseum. RG-1 organism.<br />

Lactritmel Agar: Flat, buff-coloured, suede-like to powdery colony with a deep redbrown<br />

reverse. Microscopic morphology as described above for the primary culture.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements, pinkish-buff-coloured, suede-like colony with a deep magenta<br />

red reverse.<br />

Hair Perforation Test: Positive.<br />

Microsporum cookei Ajello<br />

Key Features: distinctive macroconidial morphology and culture characteristics.<br />

20 µm<br />

Culture and macroconidia of Microsporum cookei.<br />

Microsporum cookei is a geophilic fungus which has been isolated from hair of small<br />

mammals showing no clinical lesions. Infection has been reported in rodents, dogs<br />

and rarely in humans. It is not known to invade hair in vivo, but produces hair perforations<br />

in vitro. M. cookei has a world-wide distribution.


Descriptions of Medical Fungi 91<br />

Microsporum ferrugineum Ota<br />

Colonies (SDA) are slow growing, forming a waxy, glabrous, convoluted thallus with a<br />

cream to buff-coloured surface and no reverse pigment. Note: surface pigmentation<br />

may vary from cream to yellow to deep red and a flatter white form sometimes occurs.<br />

Cultures rapidly become downy and pleomorphic. Microconidia or macroconidia are<br />

not produced. However, irregular branching hyphae with prominent cross walls (“bamboo<br />

hyphae”) and chlamydospores are seen. The so-called “bamboo hyphae” is a<br />

characteristic of this species. RG-2 organism.<br />

Key Features: clinical history, culture characteristics and distinctive “bamboo”<br />

hyphae.<br />

20 µm<br />

Culture and “bamboo hyphae” of Microsporum ferrugineum.<br />

Microsporum ferrugineum is an anthropophilic fungus causing epidemic juvenile tinea<br />

capitis in humans. The clinical features are similar to those of infections caused by<br />

M. audouinii. Invaded hairs show an ectothrix infection and fluoresce a greenish-yellow<br />

under Wood’s ultra-violet light. Reported from Asia (including China and Japan),<br />

USSR, Eastern Europe and Africa.


92<br />

Descriptions of Medical Fungi<br />

Microsporum fulvum Uriburu<br />

Teleomorph: Arthroderma fulvum (Stockdale) Weitzman et al.<br />

Colonies (SDA) are fast growing, flat, suede-like, tawny-buff to pinkish-buff in colour and<br />

frequently have a fluffy white advancing edge. A dark red under surface is occasionally<br />

seen, otherwise it is colourless to yellow brown. Abundant thin-walled, elongate, ellipsoidal<br />

macroconidia are formed which closely resemble those of M. gypseum, except<br />

they are longer and more bullet-shaped (clavate) with 3 to 6 septa. Numerous spiral<br />

hyphae, which are often branched are seen. Numerous pyriform to clavate microconidia<br />

are also produced but these are not diagnostic. RG-1 organism.<br />

Key Features: macroconidial morphology and culture characteristics.<br />

20 µm<br />

Culture and macroconidia of Microsporum fulvum.<br />

Microsporum fulvum is a geophilic fungus of world-wide distribution which may cause<br />

occasional infections in humans and animals. Clinical disease is similar to M. gypseum<br />

but less common. Invaded hairs show a sparse ectothrix infection but do not fluoresce<br />

under Wood’s ultra-violet light.


Descriptions of Medical Fungi 93<br />

Microsporum gallinae (Megnin) Grigorakis<br />

Colonies (SDA) are flat with a suede-like texture and are white in colour with a pinkish<br />

tinge. Some cultures show radial folding. An orange-pink “strawberry-coloured”<br />

reverse pigment is usually present. Macroconidia when present are usually five- to sixcelled,<br />

thin to thick-walled, slightly echinulate, cylindrical to clavate with narrow base<br />

and blunt tip, 15-60 x 6-10 µm. Microconidia are ovoidal to pyriform in shape. RG-2<br />

organism.<br />

Key Features: macroconidial morphology, culture characteristics and clinical lesions<br />

in chickens.<br />

Culture and macroconidia of Microsporum gallinae.<br />

20 µm<br />

Microsporum gallinae is a zoophilic fungus causing fowl favus in chickens and other<br />

fowl, affecting the comb and wattles producing “white comb” lesions. A rare cause of<br />

tinea in humans. Invaded hairs show a sparse ectothrix infection but do not fluoresce<br />

under Wood’s ultra-violet light.


94<br />

Descriptions of Medical Fungi<br />

Microsporum gypseum (Bodin) Guiart & Grigorakis<br />

Teleomorphs: Arthroderma gypsea (Nannizzi) Weitzman et al.<br />

Arthroderma incurvatum (Stockdale) Weitzman et al.<br />

Colonies (SDA) are usually flat, spreading, suede-like to granular, with a deep cream<br />

to tawny-buff to pale cinnamon-coloured surface. Many cultures develop a central<br />

white downy umbo (dome) or a fluffy white tuft of mycelium and some also have a narrow<br />

white peripheral border. A yellow-brown pigment, often with a central darker brown<br />

spot, is usually produced on the reverse, however a reddish-brown reverse pigment<br />

may be present in some strains. Cultures produce abundant, symmetrical, ellipsoidal,<br />

thin-walled, verrucose, four- to six-celled macroconidia. The terminal or distal ends of<br />

most macroconidia are slightly rounded, while the proximal ends (point of attachment<br />

to hyphae) are truncate. Numerous clavate-shaped microconidia are also present, but<br />

these are not diagnostic. RG-1 organism.<br />

Key Features: distinctive macroconidia and culture characteristics.<br />

20 µm<br />

Culture and macroconidia of Microsporum gypseum.<br />

Microsporum gypseum is a geophilic fungus with a world-wide distribution which may<br />

cause infections in animals and humans, particularly children and rural workers during<br />

warm humid weather. Usually produces a single inflammatory skin or scalp lesion. Invaded<br />

hairs show an ectothrix infection but do not fluoresce under Wood’s ultra-violet<br />

light.


Descriptions of Medical Fungi 95<br />

Microsporum nanum Fuentes<br />

Teleomorph: Arthroderma obtusum (Dawson and Gentles) Weitzman et al.<br />

Colonies (SDA) are flat, cream to buff in colour with a suede-like to powdery surface<br />

texture. Young colonies have a brownish-orange pigment which deepens into a dark<br />

reddish-brown with age. Cultures produce numerous small ovoid to pyriform macroconidia<br />

with one to three (mostly 2) cells, with relatively thin, finely echinulate (rough)<br />

walls, and broad truncate bases. Many macroconidia are borne on conidiophores<br />

(stalks) which do not stain readily. Occasional clavate microconidia are present, which<br />

distinguishes M. nanum from some species of Chrysosporium. RG-2 organism.<br />

Key Features: distinctive macroconidia and culture characteristics.<br />

20 µm<br />

Culture and macroconidia of Microsporum nanum.<br />

Microsporum nanum is a geophilic and zoophilic fungus frequently causing chronic<br />

non-inflammatory lesions in pigs and a rare cause of tinea in humans. Also present in<br />

soil of pig-yards. Infections in man are usually contacted directly from pig or fomites.<br />

Invaded hairs may show a sparse ectothrix or endothrix infection but do not fluoresce<br />

under Wood’s ultra-violet light. The geographical distribution is world-wide.


96<br />

Descriptions of Medical Fungi<br />

Microsporum persicolor (Sabouraud) Guiart & Grigorakis<br />

Teleomorph: Arthroderma persicolor (Stockdale) Weitzman et al.<br />

Colonies (SDA) are generally flat, white to pinkish in colour, with a suede-like to granular<br />

texture and peripheral fringe. Reverse pigmentation is orange to red. Macroconidia<br />

are thin-walled, cigar-shaped, four- to seven-celled, 40-60 x 6-8 µm but are only rarely<br />

produced. Microconidia are abundant, spherical to pyriform. RG-2 organism.<br />

Key Features: microscopic morphology and culture characteristics.<br />

Culture and microconidia of Microsporum persicolor.<br />

20 µm<br />

Microsporum persicolor is a zoophilic fungus often occurring as a saprophyte on voles<br />

and bats. A rare cause of tinea corporis in humans. Not known to invade hair in<br />

vivo, but produces hair perforations in vitro. Distribution: Africa, Australia, Europe and<br />

North America.


Descriptions of Medical Fungi 97<br />

Mortierella wolfii Mehrotra & Baijal<br />

The genus Mortierella has now been placed in a separate order, the Mortierellales<br />

(Cavalier-Smith 1998), and the genus contains about 90 recognised species, however<br />

Mortierella wolfii is probably the only pathogenic species being an important causal<br />

agent of bovine mycotic abortion, pneumonia and systemic mycosis in New Zealand,<br />

Australia, Europe and USA.<br />

Cultures are fast growing, white to greyish white, downy, often with a broadly zonate<br />

or lobed (rosette-like) surface appearance and no reverse pigment. Sporangiophores<br />

are typically erect, delicate, 80-250 µm in height, 6-20 µm wide at the base, arising<br />

from rhizoids or bulbous swellings on the substrate hyphae and terminating with<br />

a compact cluster of short acrotonous (terminal) branches. Sporangia are usually<br />

15-48 µm in diameter, with transparent walls and a conspicuous collarette is usually<br />

present following dehiscence of the sporangiospores. Columella are generally lacking<br />

and sporangiospores are single-celled, short-cylindrical, 6-10 x 3-5 µm, with a double<br />

membrane. Chlamydospores with or without blunt appendages (amoeba-like) may be<br />

present, zygospores have not been observed. Temperature: grows well at 40-42 O C;<br />

maximum 48 O C. RG-2 organism.<br />

Key Features: zygomycete, rapid growth at 40 O C (thermotolerant), and characteristic<br />

delicate acrotonous branching sporangia without columellae.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980), Rippon (1988), Smith (1989) and de Hoog et al. (2000).<br />

20 µm<br />

20 µm<br />

Culture of M. wolfii showing a broadly zonate or lobed rosette-like surface appearance<br />

and sporangium, showing a sporangiophore, wide at the base, arising from rhizoids,<br />

and acrotonous (terminal) branches, collarettes and sporangiospores.


98<br />

Descriptions of Medical Fungi<br />

Mucor Micheli ex Staint-Amans<br />

The genus Mucor can be differentiated from Absidia, Rhizomucor and Rhizopus by the<br />

absence of stolons and rhizoids. Colonies are very fast growing, cottony to fluffy, white<br />

to yellow, becoming dark-grey, with the development of sporangia. Sporangiophores<br />

are erect, simple or branched, forming large (60-300 µm in diameter), terminal, globose<br />

to spherical, multispored sporangia, without apophyses and with well-developed<br />

subtending columellae. A conspicuous collarette (remnants of the sporangial wall) is<br />

usually visible at the base of the columella after sporangiospore dispersal. Sporangiospores<br />

are hyaline, grey or brownish, globose to ellipsoidal, and smooth-walled or<br />

finely ornamented. Chlamydospores and zygospores may also be present.<br />

Key Features: zygomycete, large, spherical, non-apophysate sporangia with pronounced<br />

columellae and conspicuous collarette at the base of the columella following<br />

sporangiospore dispersal.<br />

Antifungal<br />

20 µm 20 µm<br />

Sporangia, columella with a conspicuous collarette (arrow)<br />

and sporangiospores of Mucor.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC<br />

Antifungal<br />

Range MIC 90 90<br />

Fluconazole >64 >64 Amphotericin B 0.03-4 1<br />

Itraconazole 0.125-8 2 Flucytosine >256 >256<br />

Posaconazole 0.06-8 1 Voriconazole 8->64 >64<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Sun et al. (2002), Dannaoui et al. (2003), Espinel-Ingroff (2001, 2003), Singh et al.<br />

(2005), Sabatelli et al. (2006) and WCH in-house data.


Descriptions of Medical Fungi 99<br />

Mucor Micheli ex Staint-Amans<br />

The genus Mucor contains about 50 recognised taxa, many of which have widespread<br />

occurrence and are of considerable economic importance (Zycha et al. 1969, Schipper<br />

1978, Domsch et al. 1980). However, only a few thermotolerant species are of<br />

medical importance and human infections are only rarely reported. Most infections<br />

reported list M. circinelloides and similar species such as M. indicus (M. rouxii), M. ramosissimus<br />

and M. amphibiorum as the causative agents. However, M. hiemalis and<br />

M. racemosus have also been reported as infectious agents, although their inability to<br />

grow at temperatures above 32 O C raises doubt as to their validity as human pathogens<br />

and their pathogenic role may be limited to cutaneous infections (Scholer et al. 1983,<br />

Goodman and Rinaldi 1991, Kwon-Chung and Bennett 1992, de Hoog et al. 2000).<br />

Maximum temperature for growth of the reported pathogenic species of Mucor.<br />

Species Max temp. ( O C) Pathogenicity<br />

M. amphibiorum 36 Animals, principally amphibians<br />

M. circinelloides 36-40 Animals, occasionally humans<br />

M. hiemalis 30 Questionable cutaneous infections only<br />

M. indicus 42 Humans and animals<br />

M. racemosus 32 Questionable<br />

M. ramosissimus 36 Humans and animals<br />

For descriptions of species, keys to taxa and additional information see Schipper<br />

(1978), Domsch et al. (1980), McGinnis (1980), Onions et al. (1981), Scholer et al.<br />

(1983), Rippon (1988), Goodman and Rinaldi (1991), Samson et al. (1995), de Hoog<br />

et al. (2000), Schipper and Staplers (2003) and Ellis (2005b).<br />

Mucor amphibiorum Schipper<br />

Colonies are greyish-brown, slightly aromatic and do not grow at 37 O C (maximum<br />

temperature for growth is 36 O C). Sporangiophores are hyaline, erect and mostly unbranched,<br />

rarely sympodially branched. Sporangia are dark-brown, up to 75 µm in<br />

diameter, and are slightly flattened with a diffluent membrane. Columellae are subglobose<br />

to ellipsoidal or pyriform, up to 60 x 50 µm, with small collarettes. Sporangiospores<br />

are smooth-walled, spherical, and 3.5-5.5 µm in diameter. Zygospores,<br />

when formed by compatible mating types, are spherical to slightly compressed, up to<br />

70 x 60 µm in diameter, with stellate projections. Mucor amphibiorum is distinguished<br />

by poor ramification of the sporangiophores and by globose sporangiospores. Ethanol<br />

and nitrate are not assimilated (Schipper 1978, Scholer et al. 1983, Hoog et al. 2000).<br />

RG-2 organism.


100<br />

Descriptions of Medical Fungi<br />

Mucor circinelloides v. Tiegh<br />

M. circinelloides is a common and variable species that includes 4 forms: circinelloides,<br />

lusitanicus, griseo-cyanus and janssenii (Schipper 1978, Scholer et al. 1983). Colonies<br />

are floccose, pale greyish-brown and grow poorly at 37 O C (maximum growth temperature<br />

36-40 O C). Sporangiophores are hyaline and mostly sympodially branched with<br />

long branches erect and shorter branches becoming circinate (recurved). Sporangia<br />

are spherical, varying from 20-80 µm in diameter, with small sporangia often having a<br />

persistent sporangial wall. Columellae are spherical to ellipsoidal and are up to 50 µm<br />

in diameter. Sporangiospores are hyaline, smooth-walled, ellipsoidal, and 4.5-7 x 3.5-<br />

5 µm in size. Chlamydospores are generally absent. Zygospores are only produced<br />

in crosses of compatible mating types and are reddish-brown to dark-brown, spherical<br />

with stellate spines, up to 100 µm in diameter and have equal to slightly unequal suspensor<br />

cells. M. circinelloides differs from other species of Mucor in its formation of<br />

short circinated (coiled), branched sporangiophores bearing brown sporangia and its<br />

ability to assimilate ethanol and nitrate (Schipper 1976, Scholer et al. 1983, Samson et<br />

al. 1995, de Hoog et al. 2000, Schipper and Staplers 2003). RG-1 organism.<br />

Mucor indicus Lendner<br />

Colonies are characteristically deep-yellow, aromatic and have a maximum growth<br />

temperature of 42 O C. Sporangiophores are hyaline to yellowish, erect or rarely circinate<br />

and repeatedly sympodially branched, with long branches. Sporangia are yellow<br />

to brown, up to 75 µm in diameter, with diffluent membranes. Columellae are subglobose<br />

to pyriform, often with truncate bases, up to 40 µm high. Sporangiospores are<br />

smooth-walled, subglobose to ellipsoidal, and 4-5 µm in diameter. Chlamydospores<br />

are produced in abundance, especially in the light. Zygospores when formed by crosses<br />

of compatible mating strains are black, spherical up to 100 µm in diameter, with<br />

stellate spines and unequal suspensor cells. Mucor indicus differs from other species<br />

of Mucor by its characteristic deep-yellow colony colour, growth at over 40 O C, assimilating<br />

ethanol, but not nitrate, and being thiamine dependent (Schipper 1978, de Hoog<br />

et al. 2000, Schipper and Staplers 2003). RG-1 organism.<br />

Mucor ramosissimus Samutsevich<br />

Colonial growth is restricted, greyish and does not grow at 37 O C (maximum temperature<br />

for growth is 36 O C). Sporangiophores are hyaline, slightly roughened, tapering<br />

towards the apex and are erect with repeated sympodial branching. Sporangia are<br />

grey to black, globose or somewhat flattened, up to 80 µm in diameter and have very<br />

persistent sporangial walls. Columellae are applanate (flattened), up to 40-50 µm in<br />

size and are often absent in smaller sporangia. Sporangiospores are faintly brown,<br />

smooth-walled, subglobose to broadly ellipsoidal, 5-8 x 4.5-6 µm in size. Oidia may be<br />

present in the substrate hyphae, chlamydospores and zygospores are absent. Assimilation<br />

of ethanol is negative and that of nitrate is positive. Mucor ramosissimus differs<br />

from other species of Mucor by its low, restricted growth on any medium, extremely persistent<br />

sporangial walls, columellae that are applanate or absent in smaller sporangia<br />

(often resembling Mortierella species), short sporangiophores that repeatedly branch<br />

sympodially as many as 12 times, and the occurrence of racket-shaped enlargements<br />

in the sporangiophores (Hesseltine and Ellis 1964, Schipper 1976, Scholer et al. 1983,<br />

de Hoog et al. 2000, Schipper and Staplers 2003). RG-1 organism.


Descriptions of Medical Fungi 101<br />

Nattrassia mangiferae (H. Syd. & Syd) Sutton & Dyko<br />

Pycnidial synanamorph: Hendersonula toruloidea Nattras<br />

Arthroconidial synanamorph: Scytalidium dimidiatum (Penzig) Sutton & Dyko<br />

Scytalidium hyalinum Campbell & Mulder<br />

This coelomycete is characterised by the presence of black, ostiolate pycnidia containing<br />

numerous hyaline, flask-shaped phialides. Phialoconidia are at first one-celled and<br />

hyaline, later becoming three-celled and brown, with the centre cell darker than the end<br />

cells. Conidia are ovoid to ellipsoidal in shape. Pycnidia are only occasionally formed<br />

in older cultures. In culture the Scytalidium dimidiatum anamorph is typically present<br />

showing chains of one- to two-celled, darkly pigmented arthroconidia, 3.5-5 x 6.5-12<br />

µm, produced by the holothallic fragmentation of undifferentiated hyphae. Cultures are<br />

effuse, hairy, dark grey to blackish-brown, or white to greyish, with a cream-coloured to<br />

deep ochraceous-yellow colony reverse. Colourless (hyaline) mutants (=Scytalidium<br />

hyalinum) often occur.<br />

Nattrassia mangiferae (arthric synanamorph = Scytalidium dimidiatum) is a recognised<br />

agent of onychomycosis and superficial skin infections, especially in tropical regions.<br />

However, isolates are sensitive to cycloheximide (actidione) which is commonly added<br />

to primary isolation media used for culturing skin scrapings. RG-2 organism.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Moore (1986), Rippon (1988), Frankel and Rippon (1989), Sutton and Dyko<br />

(1989) and de Hoog et al. (2000).<br />

20 µm<br />

Microscopic morphology of the Scytalidium dimidiatum synanamorph of Nattrassia<br />

mangiferae showing chains of one- to two-celled, darkly pigmented<br />

arthroconidia.<br />

Antifungal<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-2 Itraconazole 0.03-32 Voriconazole 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001) and WCH in-house data.


102<br />

Descriptions of Medical Fungi<br />

Ochroconis gallopava (W.B. Cooke) de Hoog<br />

Colonies are smooth to suede-like, dry, flat, tobacco-brown to brownish-black with a<br />

dark brown diffusible pigment. Hyphae are brown with relatively thick walls. Conidiophores<br />

are mostly cylindrical to acicular, sometimes poorly differentiated, bearing a few<br />

conidia at the tip. Conidia are two-celled, subhyaline to pale brown, smooth-walled to<br />

verrucose, cylindrical to clavate, constricted at the septum, 11-18 x 2.5-4.5 µm in size,<br />

with the apical cell wider than the basal cell. A remnant of a denticle may also be seen<br />

at the conidial base. Optimum growth at 35 O C, tolerant to 40 O C. RG-2 organism.<br />

Ochroconis gallopava is a well recognised species and has been reported as an<br />

avian pathogen, especially in poultry. Occasional human infections have also been<br />

reported.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

1980, McGinnis 1980 and de Hoog et al. 2000.<br />

Antifungal<br />

10 µm<br />

10 µm<br />

Hyphae, conidiophores and conidia of Ochroconis gallopava.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-2 Itraconazole 0.03-0.5 Voriconazole 0.03-1<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff (2001) and WCH in-house data.


Descriptions of Medical Fungi 103<br />

Onychocola canadensis Sigler<br />

Teleomorph: Arachnomyces nodososetosus Sigler & Abbott<br />

Colonies grow slowly and are velvety to lanose, white to yellowish, with a brownish<br />

reverse. Arthroconidia are cylindrical to broadly ellipsoidal, one- or two-celled, hyaline<br />

to subhyaline, 4-16 x 2-5 µm in size, forming long chains. Older cultures may show<br />

broad, brown, rough-walled hyphae. RG-2 organism.<br />

Onychocola canadensis is an uncommon cause of distal and lateral subungual or white<br />

superficial onychomycosis. However, it may sometimes be present in an abnormalappearing<br />

nail as an insignificant finding, not acting as a pathogen.<br />

Key Features: slow growing, white, arthroconidial mould isolated from nails.<br />

For descriptions of species, keys to taxa and additional information see Sigler and<br />

Congly (1990), Sigler et al. (1994), Gupta et al. (1998) and de Hoog et al. (2000).<br />

Culture and arthroconidia of Onychocola canadensis.<br />

10 µm


104<br />

Descriptions of Medical Fungi<br />

Paecilomyces Bain<br />

Colonies are fast growing, powdery or suede-like, gold, green-gold, yellow-brown, lilac<br />

or tan, but never green or blue-green as in Penicillium. Phialides are swollen at their<br />

bases, gradually tapering into a rather long and slender neck, and occur solitarily, in<br />

pairs, as verticils, and in penicillate heads. Long, dry chains of single-celled, hyaline<br />

to dark, smooth or rough, ovoid to fusoid conidia are produced in basipetal succession<br />

from the phialides.<br />

The genus Paecilomyces may be distinguished from the closely related genus Penicillium<br />

by having long slender divergent phialides and colonies that are never typically<br />

green. Paecilomyces species are common environmental moulds and are seldom<br />

associated with human infection. However, some species, P. variotii, P. marquandii<br />

and P. lilacinus are emerging as causative agents of mycotic keratitis and of hyalohyphomycosis<br />

in the immunocompromised patient.<br />

Key Features: long slender divergent phialides and culture pigmentation.<br />

For descriptions of species, keys to taxa and additional information see Samson (1974),<br />

Domsch et al. (1980), McGinnis (1980), Onions et al. (1981), Rippon (1988) and de<br />

Hoog et al. (2000).<br />

a b<br />

Cultures of P. variotii (a) and P. lilacinus (b) showing colony pigmentation.


Descriptions of Medical Fungi 105<br />

Antifungal<br />

Paecilomyces lilacinus (Thom) Samson<br />

Colonies are fast growing, suede-like to floccose, vinaceous to violet-coloured. Conidiophores<br />

are erect 400-600 µm in length, bearing branches with densely clustered<br />

phialides. Conidiophore stipes are 3-4 µm wide, yellow to purple and rough-walled.<br />

Phialides are swollen at their bases, gradually tapering into a slender neck. Conidia<br />

are ellipsoidal to fusiform, smooth-walled to slightly roughened, hyaline to purple in<br />

mass, 2.5-3.0 x 2-2.2 µm, and are produced in divergent chains. Chlamydospores are<br />

absent. Growth at 38 O C. RG-1 organism.<br />

Key Features: colony pigmentation, phialides with swollen bases, and pigmented and<br />

rough-walled conidiophore stipes, absence of chlamydospores.<br />

10 µm 10 µm<br />

Conidiophores, phialides and conidia of Paecilomyces lilacinus. Note:<br />

rough-walled conidiophore (arrow).<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Amphotericin B 2-16 8 Posaconazole 0.06-2 0.5 (2)<br />

Itraconazole 0.5-16 16 Voriconazole 0.06-4 0.25 (2)<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2001, 2003), Gonzales et al. (2005), and<br />

WCH in-house data.


106<br />

Descriptions of Medical Fungi<br />

Paecilomyces variotii Bain<br />

Colonies are fast growing, powdery to suede-like, funiculose or tufted, and yellowbrown<br />

or sand-coloured. Conidiophores bearing dense, verticillately arranged branches<br />

bearing phialides. Phialides are cylindrical or ellipsoidal, tapering abruptly into a<br />

rather long and cylindrical neck. Conidia are subspherical, ellipsoidal to fusiform, hyaline<br />

to yellow, smooth-walled, 3-5 x 2-4 µm and are produced in long divergent chains.<br />

Chlamydospores are usually present, singly or in short chains, brown, subspherical to<br />

pyriform, 4-8 µm in diameter, thick-walled to slightly verrucose. RG-2 organism.<br />

Key Features: yellow-brown colony pigmentation, cylindrical phialides, and presence<br />

of chlamydospores.<br />

10 µm 5 µm 10 µm<br />

Conidiophores, phialides, conidia and terminal chlamydospores of P. variotii.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Amphotericin B 0.06-1 1 Posaconazole 0.03-0.5 0.5<br />

Itraconazole 0.03-8 0.5 Voriconazole 0.03-2 0.5<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003) and WCH in-house data.


Descriptions of Medical Fungi 107<br />

Paracoccidioides brasiliensis (Splendore) Almeida<br />

Colonies (SDA) at 25 O C are slow growing and variable in morphology. Colonies may<br />

be flat, wrinkled and folded, glabrous, suede-like or downy in texture, white to brownish<br />

with a tan or brown reverse. Microscopically, a variety of conidia may be seen, including<br />

pyriform microconidia, chlamydospores and arthroconidia. However, none of these<br />

are characteristic of the species, and most strains may grow for long periods of time<br />

without the production of conidia.<br />

On BHI blood agar at 37 O C, the mycelium converts to the yeast phase and colonies<br />

are white to tan, moist and glabrous and become wrinkled, folded and heaped. Microscopically,<br />

numerous large, 20-60 μm, round, narrow base budding yeast cells are<br />

present. Single and multiple budding occurs, the latter are thick-walled cells that form<br />

the classical “steering wheel” or “mickey mouse” structures that are diagnostic for this<br />

fungus, especially in methenamine silver stained tissue sections.<br />

WARNING: RG-3 Organism. Cultures of Paracoccidioides brasiliensis may represent<br />

a biohazard to laboratory personnel and should be handled with extreme caution in an<br />

appropriate pathogen handling cabinet. P. brasiliensis is geographically restricted to<br />

areas of South and Central America (Rippon, 1988).<br />

Key Features: clinical history, tissue pathology, culture identification with conversion<br />

to yeast phase at 37 O C.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Chandler et al. (1980), Rippon (1988) and de Hoog et al. (2000).<br />

20 µm<br />

20 µm<br />

Multiple, narrow base budding yeast cells “steering wheels” of P. brasiliensis.<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Amphotericin B 0.03-4 0.25 Itraconazole 0.03-1 0.06<br />

Fluconazole 0.125-64 na Voriconazole 0.03-2 na<br />

Limited data available. Espinel-Ingroff et al. (2001), Espinel-Ingroff (2001) and<br />

Sabatelli et al. (2006) (na = not available).


108<br />

Descriptions of Medical Fungi<br />

Penicillium Link: Fries<br />

Colonies are usually fast growing, in shades of green, sometimes white, mostly consisting<br />

of a dense felt of conidiophores. Microscopically, chains of single-celled conidia<br />

are produced in basipetal succession from a specialised conidiogenous cell called<br />

a phialide. The term basocatenate is often used to describe such chains of conidia<br />

where the youngest conidium is at the basal or proximal end of the chain. In Penicillium,<br />

phialides may be produced singly in groups or from branched metulae, giving a<br />

brush-like appearance (a penicillus). The penicillus may contain both branches and<br />

metulae (penultimate branches which bear a whorl of phialides). All cells between the<br />

metulae and the stipes of the conidiophores are referred to as branches. The branching<br />

pattern may be either simple (non-branched or monoverticillate), one-stage branched<br />

(biverticillate-symmetrical), two-stage branched (biverticillate-asymmetrical) or three-<br />

to more-staged branched. Conidiophores are hyaline, smooth or rough-walled. Phialides<br />

are usually flask-shaped, consisting of a cylindrical basal part and a distinct neck,<br />

or lanceolate (more or less with a narrow basal part tapering to a somewhat pointed<br />

apex). Conidia are in long dry chains, divergent or in columns, are globose, ellipsoidal,<br />

cylindrical or fusiform, hyaline or greenish, smooth or rough-walled. Sclerotia are<br />

produced by some species. RG-1 organisms, with the exception of P. marneffei which<br />

is an RG-3 organism.<br />

For identification, isolates are usually inoculated at three points on Czapek Dox agar<br />

and 2% Malt extract agar and incubated at 25 O C. Most species sporulate within 7<br />

days. Microscopic mounts are best made using a cellotape flag or a slide culture<br />

preparation mounted in lactophenol cotton blue. A drop of alcohol is usually needed to<br />

remove bubbles and excess conidia (see Samson et al., 1995).<br />

Key Features: hyphomycete, flask-shaped phialides arranged in groups from branched<br />

metulae forming a penicillus.<br />

metulae<br />

branches<br />

phialides<br />

a b c d<br />

Morphological structures and types of conidiophore branching in Penicillium.<br />

(a) simple; (b) one-stage branched; (c) two-stage branched; (d) three-stage<br />

branched (see Samson et al. 1995).


Descriptions of Medical Fungi 109<br />

Penicillium Link:Fries<br />

Many species of Penicillium are common contaminants on various substrates and are<br />

known as potential mycotoxin producers. Correct identification is therefore important<br />

when studying possible Penicillium contamination of food. In some species odour and<br />

exudate production will help to recognise the taxa, but it should be pointed out that<br />

inhalation of conidia and volatiles may affect health. Human pathogenic species are<br />

rare, however opportunistic infections leading to mycotic keratitis, otomycosis and endocarditis<br />

(following insertion of valve prosthesis) have been reported (see Samson et<br />

al., 1995 and Rippon, 1988).<br />

For descriptions of species, keys to taxa and additional information see Raper and<br />

Thom (1949), Pitt (1979), Domsch et al. (1980), McGinnis (1980), Onions et al. (1981),<br />

Ramirez (1982), Samson et al. (1995) and de Hoog et al. (2000).<br />

20 µm 20 µm<br />

Conidiophores of P. verrucosum var. cyclopium showing two-stage branching. Simple<br />

conidiophore of P. cheresanum showing long chains of single-celled conidia.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Amphotericin B 0.125-2 1-2 Posaconazole 0.03-2 0.25-1<br />

Itraconazole 0.03-2 0.5-2 Voriconazole 0.03->8 0.5-2<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Pfaller et al. (2002), Diekema et al. (2003), Espinel-Ingroff (2003) and WCH in-house<br />

data.


110<br />

Descriptions of Medical Fungi<br />

Penicillium marneffei Segretain<br />

Colonies (SDA) at 25 O C are fast growing, suede-like to downy, white with yellowishgreen<br />

conidial heads. Colonies become greyish-pink to brown with age and produce<br />

a diffusible brownish-red to wine-red pigment. Conidiophores are hyaline, smoothwalled<br />

and bear terminal verticils of 3-5 metulae, each bearing 3-7 phialides. Conidia<br />

are globose to subglobose, 2 to 3 µm in diameter, smooth-walled and are produced in<br />

basipetal succession from the phialides.<br />

On brain heart infusion (BHI) blood agar incubated at 37 O C, colonies are rough, glabrous,<br />

tan-coloured and yeast-like. Microscopically, yeast cells are spherical to ellipsoidal,<br />

2-6 µm in diameter, and divide by fission rather than budding. Numerous short<br />

hyphal elements are also present.<br />

WARNING: RG-3 organism. Cultures of Penicillium marneffei may represent a biohazard<br />

to laboratory personnel and should be handled with caution in an appropriate<br />

pathogen handling cabinet. P. marneffei exhibits thermal dimorphism and is endemic<br />

in Southeast Asia and the southern region of China.<br />

Tissue sections show small, oval to elliptical yeast-like cells, 3 µm in diameter, either<br />

packed within histiocytes or scattered through the tissue. Occasional, large, elongated<br />

sausage-shaped cells, up to 8 µm long, with distinctive septa may be present.<br />

5 µm<br />

15 µm 5 µm<br />

Colony, a giemsa stained touch smear showing typical septate yeast-like cells<br />

(arrow), phialides and conidia of Penicillium marneffei.


Descriptions of Medical Fungi 111<br />

Phaeoacremonium parasiticum (Ajello et al.) W. Gams et al.<br />

Synonym: Phialophora parasiticum Ajello, Gerog & Wang<br />

Cultures are usually slow growing, suede-like with radial furrows, initially whitish-grey<br />

becoming olivaceous-grey with age. Hyphae hyaline, later becoming brown and some<br />

becoming rough-walled. Phialides are brown, thick-walled, slender, acular to cylindrical<br />

slightly tapering towards the tip, 15-50 μm long, often proliferating, with small, funnel-shaped<br />

collarettes. Conidia, often in balls, are hyaline, thin-walled, cylindrical to<br />

sausage-shaped, 3-6 x 1-2 μm, later inflating (de Hoog et al. 2000). RG-2 organism.<br />

P. parasiticum is a plant pathogen but it has also been reported from cases of<br />

subcutaneous infection, arthritis, mycetoma, endocarditis and mycotic keratitis.<br />

For descriptions of species and additional information see de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

10 µm<br />

Colony, phialides and conidia of Phaeoacremonium parasiticum.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.06-16 Itraconazole 0.06-32 Voriconazole 0.06-2<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


112<br />

Descriptions of Medical Fungi<br />

Phialophora Medlar<br />

Colonies are usually slow growing, grey to olivaceous-black, often becoming brown<br />

with age. Microscopically, members of the genus Phialophora produce clusters of<br />

single-celled conidia in basipetal succession from characteristic flask-shaped or cylindrical<br />

phialides which have distinctive collarettes. Conidia are hyaline to olivaceous<br />

brown, smooth-walled, ovoid to cylindrical or allantoid, and usually aggregate in slimy<br />

heads at the apices of the phialides, which may be solitary, or in a brush-like arrangement.<br />

The genus Phialophora contains more than 40 species, most are saprophytes commonly<br />

found in soil or on decaying wood. However, several species have been documented<br />

as causing either chromoblastomycosis (P. verrucosa) or phaeohyphomycosis<br />

(P. verrucosa and P. richardsiae).<br />

Phialophora richardsiae (Nannf.) Conant<br />

Colonies grow rapidly, and are powdery to woolly or tufted, greyish-brown with a greybrown<br />

to olivaceous-black reverse. Two conidial types are produced; (1) hyaline conidia<br />

which are allantoid or cylindrical, 3-6 x 1.5-2.5 μm in size, formed on inconspicuous,<br />

peg-like phialides on thin-walled hyphae; and (2) brown, thick-walled conidia which are<br />

spherical to sub-spherical, 2.5-3.5 x 2-3 μm, formed on dark brown, slender, tapering<br />

phialides with flaring collarettes. RG-2 organism.<br />

Phialophora richardsiae is a soft rot fungus of wood and is an uncommon cause of<br />

human infection. However, cases of subcutaneous phaeohyphomycosis have been<br />

reported.<br />

Antifungal<br />

10 µm<br />

10 µm<br />

Phialides of P. richardsiae producing 2 types of conidia. (1) hyaline conidia, formed on<br />

inconspicuous, peg-like phialides on thin-walled hyphae; and (2) brown, thick-walled<br />

conidia formed on dark brown, slender, tapering phialides with flaring collarettes.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.125-1 Itraconazole 0.03-2 Voriconazole 0.125-2<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


Descriptions of Medical Fungi 113<br />

Phialophora verrucosa Medlar<br />

Colonies (SDA) are slow growing, initially dome-shaped, later becoming flat, suedelike<br />

and olivaceous to black in colour. Phialides are flask-shaped or elliptical with distinctive<br />

funnel-shaped, darkly pigmented collarettes. Conidia are ellipsoidal, smoothwalled,<br />

hyaline, mostly 3.0-5.0 x 1.5-3.0 μm, and aggregate in slimy heads at the<br />

apices of the phialide. RG-2 organism.<br />

Phialophora verrucosa is a well documented causative agent of chromoblastomycosis,<br />

and mycetoma. It produces characteristic flask-shaped phialides with distinctive funnel-shaped,<br />

darkly pigmented collarettes.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971),<br />

McGinnis (1978), Domsch et al. (1980), McGinnis (1980) and de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

20 µm<br />

Phialides and conidia of Phialophora verrucosa.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-4 Itraconazole 0.03-0.06 Voriconazole 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


114<br />

Descriptions of Medical Fungi<br />

Phoma Saccardo<br />

Colonies are spreading, greyish-brown, powdery or suede-like and produce large,<br />

globose, membranous to leathery, darkly pigmented, ostiolate pycnidia. Conidia are<br />

produced in abundance within the pycnidia on narrow thread-like phialides, which are<br />

hardly differentiated from the inner pycnidial wall cells. Conidia are globose to cylindrical,<br />

one-celled, hyaline, and are usually extruded in slimy masses from the apical<br />

ostiole. RG-1 organism.<br />

Members of the genus Phoma have a world-wide distribution and are ubiquitous in<br />

nature, with over 2000 species having been described from soil, as saprophytes on<br />

various plants, and as pathogens to plants and humans.<br />

Key Features: coelomycete, ostiolate pycnidia producing masses of slimy, hyaline,<br />

single-celled conidia.<br />

For descriptions of species, keys to taxa and additional information see Punithalingam<br />

(1979), McGinnis (1980), Sutton (1980), Rippon (1988), Montel et al. (1991), Samson<br />

et al. (1995) and de Hoog et al. (2000).<br />

20 µm<br />

Pycnidia of Phoma.


Descriptions of Medical Fungi 115<br />

Pithomyces Berkeley and Broome<br />

Colonies are fast growing, dark grey to black, suede-like to downy and produce darkly<br />

pigmented, multicellular conidia formed on small peg-like branches of the vegetative<br />

hyphae. Conidia are broadly elliptical, pyriform, oblong, and are commonly echinulate<br />

or verrucose.<br />

The genus Pithomyces contains about 15 species commonly found from a very wide<br />

range of plant material, also from air, soil, hay, sawn timber and ceiling plaster. However,<br />

one species, Pithomyces chartarum is often involved with facial eczema of sheep.<br />

Pithomyces chartarum (Berk. & M.A. Curtis) M.B. Ellis<br />

Colonies are fast growing, suede-like to downy and black. Conidiophores are pale olive,<br />

smooth or verrucose, 2.5-10 x 2-3.5 µm. Conidiogenous cells integrated, intercalary<br />

or terminal, indeterminate, with 1-2 loci of similar width in the conidiogenous cells.<br />

Conidia muriform, medium to dark brown, echinulate to verrucose, 3 (-4)-euseptate,<br />

slightly constricted at the septa, with one or both median cells divided by longitudinal<br />

septa, thick-walled, broadly ellipsoidal, apex obtuse, base truncate and characteristically<br />

with part of the conidiogenous cell remaining attached as a small pedicel, 18-29<br />

x 10-17 µm. RG-1 organism.<br />

Key Features: dematiaceous hyphomycete with multi-celled conidia produced on<br />

small peg-like branches of the vegetative hyphae.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971 and<br />

1976), Domsch et al. (1980) and Rippon (1988).<br />

15 µm<br />

Conidiophores and conidia of Pithomyces chartarum.


116<br />

Descriptions of Medical Fungi<br />

Prototheca Kruger<br />

Prototheca species are achlorophyllous algae with phylogenetic affinities to the genus<br />

Chlorella. Colonies are smooth, moist, white to cream and yeast-like. Cultures are<br />

sensitive to cycloheximide (actidione) and optimal growth occurs at 25 O C to 30 O C.<br />

Mycelium and conidia are absent. Vegetative cells are globose to ovoid, hyaline, varying<br />

in size from approximately 8-20 µm, and have a relatively thick and highly refractile<br />

wall. No budding cells are present; reproduction is by the development of large sporangia<br />

(theca) which contain from 2-20 or more small sporangiospores (endospores or<br />

autospores) which are asexually produced by nuclear division and cleavage of the cytoplasm<br />

(Kaplan, 1977, McGinnis, 1980, Rippon, 1988, Pore, 1985). RG-1 organism.<br />

Key Features: achlorophyllous algae reproducing by sporangia (theca) and sporangiospores<br />

(autospores). The genus Prototheca contains four species which can be<br />

differentiated by assimilation tests and morphological criteria as outlined below. The<br />

API 20C yeast identification strip may be used for species identification. So far only P.<br />

wickerhamii and P. zopfii have been involved in human or animal infections.<br />

P. wickerhamii P. zopfii P. stagnora P. moriformis<br />

Growth at 37 O C + + - -<br />

Glucose + + + +<br />

Trehalose + - - -<br />

L-propanol - + +/- +<br />

Acetate (pH5) - + +/- +<br />

Galactose + - + -<br />

Capsule - - + +<br />

Antifungal<br />

5 µm<br />

Thecae and autospores of Prototheca wickerhamii.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal<br />

Antifungal<br />

Range Range Range<br />

Amphotericin B 0.25-0.5 Voriconazole 0.25 Posaconazole 0.25<br />

WCH in-house data only.


Descriptions of Medical Fungi 117<br />

Ramichloridium Stahel ex de Hoog<br />

Colonies are rapid growing, smooth, farinose or velvety, brown or olivaceous-green,<br />

often with orange or yellow soluble pigments. Conidiophores are erect, brown, apically<br />

with small denticles on which conidia are produced in sympodial succession. Conidia<br />

are one-celled, hyaline to pale brown.<br />

Ramichloridium contains about 25 species that are usually associated with forest litter<br />

and rotting wood, however the genus contains two species of medical interest; R.<br />

mackenziei and R. schulzeri.<br />

Ramichloridium schulzeri (Sacc.) de Hoog<br />

Colonies growing moderately rapidly, consisting of a rather compact, flat, submerged<br />

mycelium, pale orange, locally with some powdery, brownish aerial mycelium; reverse<br />

pink to orange. Conidiophores are erect, straight, unbranched, thick-walled, reddishbrown,<br />

up to 250 µm high, gradually becoming paler towards the apex, of variable<br />

length, elongating sympodially during conidiogenesis, with scattered, pimple-shaped<br />

conidium bearing denticles which have unpigmented scars. Conidia are subhyaline,<br />

smooth-walled or slightly rough-walled, ellipsoidal, obovoidal or fusiform, 6.5-10.0 x 3-<br />

4 µm, usually with an acuminate base and unpigmented scars. RG-1 organism.<br />

For descriptions of species, keys to taxa and additional information see de Hoog (1977),<br />

Rippon et al. (1985) and de Hoog et al. (2000).<br />

10 µm<br />

20 µm<br />

Conidiophores showing sympodial development of conidia of R. schulzeri.


118<br />

Descriptions of Medical Fungi<br />

Rhinocladiella Nannfeldt<br />

Colonies are restricted, velvety, lanose or nearly smooth, grey to olivaceous-brown.<br />

Hyphae pale olivaceous. Conidiophores are slightly differentiated, sub-erect, usually<br />

branched, pale to dark brown. Conidiogenous cells are intercalary or free, cylindrical,<br />

in the apical part with conidium bearing denticles with unpigmented scars. Conidia are<br />

hyaline to subhyaline, one-celled and smooth-walled. Budding cells and an accompanying<br />

Exophiala state may be present.<br />

Rhinocladiella contains 6-8 species, with two species of medical interest; R. atrovirens<br />

and R. aquaspersa.<br />

Rhinocladiella atrovirens Nannfeldt<br />

Colonies are restricted, velvety or lanose, olivaceous, often slightly mucoid at the centre;<br />

reverse dark olivaceous green to blackish. Conidiophores are short, brown, thickwalled.<br />

Conidiogenous cells are cylindrical, intercalary or free, 9-19 x 1.6-2.2 µm;<br />

denticulate rachis up to 15 µm long, with crowded, flat or butt-shaped, unpigmented<br />

conidial denticles. Conidia are hyaline, thin- and smooth-walled, short-cylindrical,<br />

with truncate basal scars, 3.7-5.5 x 1.2-1.8 µm. Budding cells, if present, are hyaline,<br />

thin-walled, broadly ellipsoidal, 3.0-4.3 x 1.7-2.5 µm. Germinating cells are inflated,<br />

spherical to subspherical, 4.5-6.0 µm. An annellidic Exophiala synanamorph may be<br />

present. RG-1 organism.<br />

For descriptions of species, keys to taxa and additional information see de Hoog (1977,<br />

1983), Schell et al. (1983) and de Hoog et al. (2000).<br />

Antifungal<br />

10 µm 10 µm 10 µm<br />

Culture, conidiophores showing a terminal denticulate rachis, conidia and budding<br />

yeast cells of Rhinocladiella atrovirens.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.03-0.25 Itraconazole 0.03-0.06 Voriconazole 0.03-0.5<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998), Espinel-Ingroff et al. (2001) and WCH in-house data.


Descriptions of Medical Fungi 119<br />

The genus Rhizomucor is distinguished from Mucor by the presence of stolons and<br />

poorly developed rhizoids at the base of the sporangiophores and by the thermophilic<br />

nature of its 3 species: R. miehei, R. pusillus and R. tauricus. All 3 of these species<br />

are potential human and animal pathogens and were originally classified in the genus<br />

Mucor. Rhizomucor variabilis as described by de Hoog et al. (2000) is not thermophilic<br />

and is probably a degenerate culture of Mucor hiemalis (Voigt et al., 1999). Rhizomucor<br />

pusillus is cosmopolitan and both R. miehei and R. pusillus have been reported as<br />

pathogens to humans and animals, the latter to a greater extent.<br />

For descriptions of species, keys to taxa and additional information see Cooney and<br />

Emerson (1964), Schipper (1978), Domsch et al. (1980), McGinnis (1980), Ellis and<br />

Keane (1981), Scholer et al. (1983), Hoog et al. (2000), Schipper and Staplers (2003)<br />

and Ellis (2005b).<br />

Remember, identification of most zygomycetes is based primarily on the morphology<br />

of the sporangia; i.e. arrangement and number of sporangiospores, shape, colour,<br />

presence or absence of columellae and apophyses, as well as the arrangement of the<br />

sporangiophores and the presence or absence of rhizoids. Growth temperature tests<br />

can also be especially helpful in identifying and differentiating members of the genera<br />

Rhizomucor, Rhizopus and Absidia.<br />

Rhizomucor miehei (Cooney and Emerson) Schipper<br />

Synonym: Mucor miehei Lindt<br />

This species has been reported as a rare cause of bovine mastitis (Scholer et al. 1983)<br />

and is similar in most respects to R. pusillus. However, all strains are homothallic<br />

forming numerous zygospores, which are reddish-brown to blackish-brown, globose to<br />

slightly compressed, up to 50 µm in diameter, with stellate warts and equal suspensor<br />

cells. Colony colour is a dirty grey rather than brown, and sporangia have spiny walls,<br />

are up to 50-60 µm in diameter, with columellae rarely larger than 30 µm in diameter.<br />

Growth is stimulated by thiamine, with no assimilation of sucrose and maximum temperature<br />

of growth is 54–58 O C. RG-1 organism.<br />

Key Features: growth at 45 O C, the formation of numerous zygospores, a dirty grey<br />

culture colour and a partial growth requirement for thiamine.<br />

Synonym: Mucor pusillus Lindt<br />

Rhizomucor Lucet & Costantin<br />

Rhizomucor pusillus (Lindt) Schipper<br />

This species is a rare human pathogen. It has been reported from cases of pulmonary,<br />

disseminated and cutaneous types of infection. It is more often associated with animal<br />

disease, especially bovine abortion. Rhizomucor pusillus has a world-wide distribution<br />

and is commonly associated with compost heaps.


120<br />

Descriptions of Medical Fungi<br />

Rhizomucor pusillus (Lindt) Schipper<br />

This thermophilic zygomycete is readily recognizable by its characteristic compact, low<br />

growing (2-3 mm high), grey to greyish brown-coloured mycelium and by the development<br />

of typical sympodially branched, hyaline to yellow-brown sporangiophores (8-15<br />

μm in diameter), always with a septum below the sporangium. Sporangia are globose<br />

(40-60 µm in diameter), each possessing an oval or pear-shaped columella (20-30<br />

µm), often with a collarette. Sporangiospores are hyaline, smooth-walled, globose to<br />

subglobose, occasionally oval (3-5 µm), and are often mixed with crystalline remnants<br />

of the sporangial wall. Chlamydospores are absent. Zygospores are rough-walled,<br />

reddish brown to black, 45-65 mm in diameter and may be produced throughout the<br />

aerial hyphae in matings between compatible isolates. Temperature growth range:<br />

minimum 20-27 O C; optimum 35-55 O C; maximum 55-60 O C. There is positive assimilation<br />

of sucrose and no thiamine dependence. RG-2 organism.<br />

Key Features: zygomycete, growth at 45 O C (thermophilic), poorly developed stolons<br />

and rhizoids, branching sporangiophores with a septum below the sporangium, darkcoloured<br />

sporangia without apophyses and smooth-walled globose to subglobose<br />

sporangiospores.<br />

15 µm 20 µm<br />

Sporangiophores, collumellae and primitive rhizoids of R. pusillus.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range Range<br />

Fluconazole >64 Amphotericin B 0.06-0.25<br />

Itraconazole 0.03-0.25 Flucytosine >256<br />

Posaconazole 0.06-0.25 Voriconazole 2-16<br />

Very limited data, antifungal susceptibility testing of individual strains is<br />

recommended. Dannaoui et al. (2003), Singh et al. (2005) and WCH inhouse<br />

data.


Descriptions of Medical Fungi 121<br />

The genus Rhizopus is characterised by the presence of stolons and pigmented rhizoids,<br />

the formation of sporangiophores, singly or in groups from nodes directly above<br />

the rhizoids, and apophysate, columellate, multispored, generally globose sporangia.<br />

After spore release the apophyses and columella often collapse to form an umbrellalike<br />

structure. Sporangiospores are globose to ovoid, one-celled, hyaline to brown<br />

and striate in many species. Colonies are fast growing and cover an agar surface with<br />

a dense cottony growth that is at first white becoming grey or yellowish brown with<br />

sporulation.<br />

Antifungal<br />

Rhizopus Ehrenberg ex Corda.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC<br />

Antifungal<br />

Range MIC 90 90<br />

Fluconazole >64 >64 Amphotericin B 0.03-4 2<br />

Itraconazole 0.25-8 4 Flucytosine >256 >256<br />

Posaconazole 0.03-8 2 Voriconazole 4->64 >64<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Sun et al. (2002), Dannaoui et al. (2003), Espinel-Ingroff (2001, 2003), Singh et al.<br />

(2005), Sabatelli et al. (2006) and WCH in-house data.<br />

In the past, numerous attempts have been made to clarify the species concepts of<br />

the genus Rhizopus. Recently, 3 excellent revisions with easy to use keys have been<br />

produced by Schipper (1984), Ellis (1985, 1986) and Schipper and Stalpers (2003).<br />

Basically, 3 groups have been recognised: the ‘stolonifer’ group, the ‘oryzae’ group and<br />

the ‘microsporus’ group. The G-C values of the 3 groups have been defined by Frye<br />

and Reinhardt (1993), and temperature growth studies at 30 O C, 36 O C and 45 O C are<br />

characteristic for each of the groups.<br />

The ‘stolonifer’ group has sporangia up to 275 µm in diameter and grows at 30 O C, but<br />

has a maximum growth temperature of 36 O C. Species in this group include R. sexualis<br />

and R. stolonifer. The latter has been unconvincingly implicated in human infection<br />

(Ferry and Abedi 1983), although with a maximum growth temperature of only 32 O C its<br />

pathogenicity is thus questionable.<br />

The ‘oryzae’ group has been reduced to a single species that is able to grow at 40 O C<br />

but not at 45 O C, and has sporangia not exceeding 240 µm in diameter. There is no<br />

doubt that R. oryzae and R. arrhizus are synonymous, the contentious issue being<br />

which species name to use. The taxonomic treatment of Schipper and Stalpers (2003)<br />

will be used in this book; however, the synonym R. arrhizus is commonly used in the<br />

medical literature. Rhizopus oryzae is an important human pathogen.<br />

The ‘microsporus’ group has simple rhizoids, and smaller sporangia up to 100 µm in<br />

diameter and grows at both 40 and 45 O C. This group contains 4 species: R. homothallicus,<br />

R. azygosporus, R. schipperae and R. microsporus with the later subdivided into<br />

3 varieties, namely R. microsporus var. microsporus, R. microsporus var. oligosporus<br />

and R. microsporus var. rhizopodiformis. All are thermophilic and R. microsporus is a<br />

well-recognised pathogen of humans and animals.


122<br />

Descriptions of Medical Fungi<br />

Rhizopus Ehrenberg ex Corda.<br />

Differentiation of pathogenic Rhizopus microsporus group isolates.<br />

Species Growth<br />

at 45O Growth<br />

C at 50O Main species characteristics<br />

C<br />

R. azygosporus Good No Abundant azygospores<br />

R. microsporus var. Good No Sporangiospores angular to ellipsoidal<br />

microsporus<br />

and distinctly striate, up to 5–6 µm diam<br />

R. microsporus var. Restricted No Sporangiospores globose, up to<br />

oligosporus<br />

9 µm diameter or more, heterogeneous<br />

R. microsporus var. Good Good Sporangiospores globose rarely over 5<br />

rhizopodiformis<br />

µm in diameter minutely spinulose<br />

R. schipperae Good No Abundant chlamydospores and<br />

restricted sporulation<br />

For descriptions of species, keys to taxa and additional information, see Domsch et al.<br />

(1980), McGinnis (1980), Onions et al. (1981), Scholer et al. (1983), Schipper (1984),<br />

Schipper and Stalpers (1984, 2003), Ellis (1985, 1986), Rippon (1988), Kwon-Chung<br />

and Bennett (1992), Samson et al. (1995); Hoog et al. (2000) and Ellis (2005b).<br />

Rhizopus azygosporus Yuan & Jong<br />

Rhizopus azygosporus is closely related to R. microsporus (Yuan and Jong 1984) and<br />

has been reported as the causative agent of 3 fatal cases of gastrointestinal infection<br />

in premature babies (Woodward et al. 1992, Schipper et al. 1996). Previously, this fungus<br />

was only known from its type culture, which has been isolated from tempeh, a solid<br />

fermented soybean food from Indonesia (Yuan and Jong 1984). Colonies are whitish<br />

to grey-black, producing pale-brown simple rhizoids. Sporangiophores are brownish,<br />

up to 350 µm high and 6-14 µm wide. Sporangia are greyish-black, spherical and<br />

50-100 µm in diameter. Columellae are subglobose to globose. Sporangiospores<br />

are ovoid to ellipsoidal 4-5 to 6-7 µm in diameter with faint striations. Azygospores<br />

are pale to dark-brown, spherical to subglobose, 30–70 µm in diameter, with coarse<br />

conical projections. All strains produce abundant azygospores in unmated isolates as<br />

a species characteristic. There is good growth at 45 O C with a maximum of 46-48 O C.<br />

RG-2 organism.<br />

Rhizopus microsporus var. microsporus<br />

Rhizopus microsporus var. microsporus is a rare cause of human infection (Kerr et al.<br />

1988, Kwon-Chung and Bennett, 1992). Colonies are pale brownish-grey producing<br />

simple rhizoids. Sporangiophores are brownish, up to 400 µm high and 10 µm wide,<br />

but most are smaller and are produced in pairs. Sporangia are greyish-black, spherical,<br />

up to 80 µm in diameter. Columellae are subglobose to globose to conical. Sporangiospores<br />

are angular to broadly ellipsoidal to lemon-shaped, quite equal in size,<br />

up to 5-6 µm in diameter and are distinctly striate. Zygospores, formed by crosses of<br />

compatible mating strains, are dark red–brown, spherical, up to 100 µm in diameter,<br />

with stellate projections and unequal suspensor cells. There is good growth at 45 O C,<br />

with a maximum of 46–48 O C. RG-2 organism.


Descriptions of Medical Fungi 123<br />

Rhizopus microsporus var. oligosporus (Saito) Schipper & Stalpers<br />

Rhizopus microsporus var. oligosporus is a rare cause of human zygomycosis (Tintelnot<br />

and Nitsche 1989). Colonies are pale yellowish-brown to grey and sporulation is<br />

often poor. Rhizoids are subhyaline and simple. Sporangiophores are brownish, up to<br />

300 µm high and 15 µm wide, with 1-3 produced together. Sporangia are black, spherical,<br />

up to 100 µm in diameter. Columellae are subglobose to somewhat conical. Sporangiospores<br />

are subglobose to globose, up to 9 µm in diameter, almost smooth, with<br />

larger spores often irregular in shape. Chlamydospores are abundant, hyaline, single<br />

or in chains, spherical, ellipsoidal or cylindrical, 7-35 µm in diameter. Zygospores are<br />

not known. There is growth at 45 O C with a maximum of 46–48 O C. RG-2 organism.<br />

Rhizopus microsporus var. rhizopodiformis (Cohn) Schipper & Stalpers<br />

Rhizopus microsporus var. rhizopodiformis is the second most frequently isolated zygomycete,<br />

accounting for between 10% and 15% of reported human cases (Scholer<br />

et al. 1983; Kwon-Chung and Bennett 1992). Colonies are dark greyish-brown, up to<br />

10 mm high with simple rhizoids. Sporangiophores are brownish, up to 500 µm high<br />

and 8 µm wide, with 1-4 produced together. Sporangia are bluish to greyish-black,<br />

spherical and up to 100 µm in diameter. Columellae are pyriform comprising 80% of<br />

the sporangium. Sporangiospores are subglobose to globose, quite equal in size, up<br />

to 6 µm in diameter and minutely spinulose. Zygospores, when formed by crosses of<br />

compatible mating strains, are reddish-brown, spherical, up to 100 µm in diameter, with<br />

stellate projections and unequal suspensor cells. There is good growth at 45 O C with a<br />

maximum of 50–52 O C. RG-2 organism.<br />

30 µm<br />

Sporangia showing sporangiophores, columellae, sporangiospores<br />

and rhizoids of R. microsporus var. oligosporus.


124<br />

Descriptions of Medical Fungi<br />

Rhizopus oryzae Went & Prinsen Geerligs<br />

Synonym: Rhizopus arrhizus Fischer<br />

Rhizopus oryzae is the most common causative agent of zygomycosis, accounting for<br />

some 60% of the reported culture positive cases, and nearly 90% of the rhinocerebral<br />

form of infection. Colonies are very fast growing, about 5-8 mm high, with some tendency<br />

to collapse, white cottony at first becoming brownish grey to blackish-grey depending<br />

on the amount of sporulation. Sporangiophores up to 1500 µm in length and<br />

18 µm in width, smooth-walled, non-septate, simple or branched, arising from stolons<br />

opposite rhizoids usually in groups of 3 or more. Sporangia are globose, often with a<br />

flattened base, greyish black, powdery in appearance, up to 175 µm in diameter and<br />

many spored. Columellae and apophysis together are globose, subglobose or oval, up<br />

to 130 µm in height and soon collapsing to an umbrella-like form after spore release.<br />

Sporangiospores are angular, subglobose to ellipsoidal, with ridges on the surface,<br />

and up to 8 µm in length. No growth at 45 O C; good growth at 40 O C. RG-2 organism<br />

20 µm<br />

100 µm<br />

Culture, sporangia, sporangiophores and rhizoids of R.oryzae.


Descriptions of Medical Fungi 125<br />

Rhodotorula Harrison<br />

The genus Rhodotorula is characterised by the combination of red or yellow cultures<br />

due to the presence of carotenoid pigments, the inability to assimilate inositol and the<br />

absence of fermentation. The basidiomycetous nature of yeasts is usually indicated<br />

by a positive urease test. The genus Cryptococcus is similar to Rhodotorula both in<br />

production of carotenoid pigments and the presence of capsulated blastoconidia. The<br />

distinctive difference between the two is the assimilation of inositol, which is positive in<br />

Cryptococcus.<br />

Rhodotorula mucilaginosa is a common airborne contaminant of skin, lungs, urine and<br />

faeces. R. mucilaginosa is a known cause of fungal peritonitis in patients on continuous<br />

ambulatory peritoneal dialysis (CAPD). This is usually due to saprophytic colonisation<br />

of catheters or dialysis machinery and removal of the source of contamination<br />

usually leads to clearing of the symptoms.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Barnett et al. (1983), Kreger-Van Rij (1984), Rippon (1988), Kurtzman and<br />

Fell (1988) and de Hoog et al. (2000).<br />

Culture of Rhodotorula mucilaginosa.


126<br />

Descriptions of Medical Fungi<br />

Rhodotorula glutinis (Fresenius) Harrison<br />

Culture: Colonies (SDA) are coral red to salmon-coloured or slightly orange, smooth<br />

to wrinkled, highly glossy to semi-glossy. Mucoid to pasty to slightly tough, yeast-like<br />

colonies.<br />

Microscopy: Ovoidal to globose or more elongate budding yeast-like cells or blastoconidia,<br />

2.3-5.0 x 4.0-10.0 µm.<br />

India Ink Preparation: Small capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Budding blastoconidia<br />

only. No pseudohyphae are formed.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose v D-Glucitol v<br />

Fermentation Sucrose + D-Arabinose v α-M-D-glucoside v<br />

Glucose - Maltose + D-Ribose v D-Gluconate +<br />

Galactose - Cellobiose v L-Rhamnose v DL-Lactate v<br />

Sucrose - Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine - 2-K-D-gluconate v<br />

Lactose - Melibiose - Glycerol v D-Glucuronate v<br />

Trehalose - Raffinose v Erythritol - Nitrate -<br />

Assimilation Melezitose + Ribitol v Urease +<br />

Glucose + Soluble Starch - Galactitol v 0.1% Cycloheximide v<br />

Galactose v D-Xylose v D-Mannitol v Growth at 37 O C v<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Common<br />

saprophyte however cases of fungemia have been reported. RG-1 organism.<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range Antifungal<br />

Range<br />

Fluconazole >64 Amphotericin B 0.06-0.25<br />

Itraconazole 0.5-1 Flucytosine 0.03-0.06<br />

Voriconazole 1-4 Caspofungin 0.25<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

WCH in-house data only.


Descriptions of Medical Fungi 127<br />

Synonym: Rhodotorula rubra (Demme) Lodder.<br />

Culture: Colonies (SDA) are coral pink, usually smooth, sometimes reticulate, rugose<br />

or corrugated, moist to mucoid, yeast-like colonies.<br />

Microscopy: Spherical to elongate budding yeast-like cells or blastoconidia, 2.5-6.5 x<br />

6.5-14.0 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Budding blastoconidia<br />

only. No pseudohyphae are formed.<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Common<br />

saprophyte however cases of peritonitis and fungemia have been reported. RG-1<br />

organism.<br />

Antifungal<br />

Rhodotorula mucilaginosa (Jorgensen) Harrison<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose v L-Arabinose v D-Glucitol v<br />

Fermentation Sucrose + D-Arabinose v α-M-D-glucoside v<br />

Glucose - Maltose v D-Ribose v D-Gluconate +<br />

Galactose - Cellobiose v L-Rhamnose v DL-Lactate v<br />

Sucrose - Trehalose + D-Glucosamine v myo-Inositol -<br />

Maltose - Lactose - N-A-D-glucosamine - 2-K-D-gluconate v<br />

Lactose - Melibiose - Glycerol v D-Glucuronate -<br />

Trehalose - Raffinose + Erythritol v Nitrate -<br />

Assimilation Melezitose v Ribitol v Urease +<br />

Glucose + Soluble Starch - Galactitol v 0.1% Cycloheximide -<br />

Galactose v D-Xylose + D-Mannitol v Growth at 40 O C +<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.5->64 >64 Amphotericin B 0.03-1 0.5<br />

Itraconazole 0.25-4 2 Flucytosine 0.03-0.25 0.25<br />

Voriconazole 0.25-4 2 Caspofungin 16 >16<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003), Cuenca-Estrella et al. (2006) and<br />

WCH in-house data.


128<br />

Descriptions of Medical Fungi<br />

Saccharomyces cerevisiae Meyen ex Hansen<br />

The genus Saccharomyces is characterised by strong fermentation of at least glucose<br />

and the presence of rather large globose to ellipsoidal cells with multilateral budding.<br />

Pseudohyphae can be formed, but never true hyphae. Ascospores are globose to ellipsoidal,<br />

with a smooth wall, usually one to four per ascus. Lactose and nitrate are<br />

not utilised. The species S. cerevisiae, commonly known as Baker’s yeast, is the most<br />

important representative.<br />

Culture: Colonies (SDA) are white to cream, smooth, glabrous yeast-like colonies.<br />

Microscopy: Large globose to ellipsoidal budding yeast-like cells or blastoconidia,<br />

3.0-10.0 x 4.5-21.0 µm.<br />

India Ink Preparation: Negative - No capsules present.<br />

Dalmau Plate Culture on Cornmeal and Tween 80 Agar: Usually budding blastoconidia<br />

only, however pseudohyphae may be formed rarely.<br />

Physiological Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Germ Tube - L-Sorbose - L-Arabinose - D-Glucitol -<br />

Fermentation Sucrose + D-Arabinose - α-M-D-glucoside v<br />

Glucose + Maltose + D-Ribose - D-Gluconate -<br />

Galactose v Cellobiose - L-Rhamnose - DL-Lactate v<br />

Sucrose + Trehalose + D-Glucosamine - myo-Inositol -<br />

Maltose v Lactose - N-A-D-glucosamine - 2-K-D-gluconate -<br />

Lactose - Melibiose v Glycerol - D-Glucuronate -<br />

Trehalose - Raffinose + Erythritol - Nitrate -<br />

Assimilation Melezitose v Ribitol - Urease -<br />

Glucose + Soluble Starch - Galactitol - 0.1% Cycloheximide -<br />

Galactose v D-Xylose - D-Mannitol - Growth at 37 O C v<br />

Key Features: germ tube negative yeast and sugar assimilation pattern. Common<br />

food and environmental saprophyte. RG-1 organism.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Barnett et al. (1983), Kreger-Van Rij (1984), Rippon (1988), Kurtzman and<br />

Fell (1988) and de Hoog et al. (2000).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 0.125-16 8 Amphotericin B 0.06-2 1<br />

Itraconazole 0.03-4 0.5 Flucytosine 0.03-0.5 0.25<br />

Voriconazole 0.06-0.25 0.125 Caspofungin 1 1<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003), Cuenca-Estrella et al. (2006)<br />

and WCH in-house data.


Descriptions of Medical Fungi 129<br />

Saksenaea vasiformis Saksena<br />

The genus Saksenaea is characterised by the formation of flask-shaped sporangia<br />

with columellae and simple, darkly pigmented rhizoids. Saksenaea vasiformis is the<br />

only known species and appears to have a world-wide distribution in association with<br />

soil. It is an emerging human pathogen (Holland, 1997) that is most often associated<br />

with cutaneous or subcutaneous lesions after trauma. Colonies are fast growing,<br />

downy, white with no reverse pigment made up of broad, non-septate hyphae typical of<br />

a zygomycetous fungus. Sporangia are typically flask-shaped with a distinct spherical<br />

venter and long-neck, arising singly or in pairs from dichotomously branched, darkly<br />

pigmented rhizoids. Collumellae are prominent and dome-shaped. Sporangiospores<br />

are small, oblong, 1-2 x 3-4 µm, and are discharged through the neck following the dissolution<br />

of an apical mucilaginous plug. RG-2 organism.<br />

Key Features: zygomycete, unique flask-shaped sporangia, failure to sporulate on<br />

primary isolation media.<br />

Laboratory identification of this fungus may be difficult or delayed because of the<br />

mould’s failure to sporulate on the primary isolation media or on subsequent subculture<br />

onto potato dextrose agar. Sporulation may be stimulated by the use of nutrient deficient<br />

media, like cornmeal-glucose-sucrose-yeast extract agar, Czapek Dox agar, or<br />

by using the agar block method described by Ellis and Ajello (1982), Ellis and Kaminski<br />

(1985) and Padhye and Ajello (1988).<br />

For descriptions of species, keys to taxa and additional information see Saksena<br />

(1953), Ellis and Hesseltine (1966), Ajello et al. (1976), Ellis and Ajello (1982), Ellis<br />

and Kaminski (1985), Pritchard et al. (1986), Padhye et al. (1988), Padhye and Ajello<br />

(1988), Goldschmied-Reouven et al. (1989), de Hoog et al. (2000) and Ellis (2005b).<br />

Antifungal<br />

The agar block method to induce<br />

sporulation of Saksenaea vasiformis<br />

and Apophysomyces elegans.<br />

A small block of agar is cut from a well<br />

established culture grown on PDA and<br />

is placed in the centre of petri dish<br />

containing 1% agar in distilled water.<br />

After 21 days at 26 O C look for sporangium<br />

formation at the periphery of the<br />

petri dish.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range Range<br />

Fluconazole >64 Amphotericin B 0.125-2<br />

Itraconazole 0.015-0.3 Flucytosine >256<br />

Posaconazole 0.015-0.25 Voriconazole 0.5-4<br />

Very limited data, poor sporulation, antifungal susceptibility testing of individual strains<br />

is recommended. Sun et al. (2002) and WCH in-house data.


130<br />

Descriptions of Medical Fungi<br />

Saksenaea vasiformis Saksena<br />

15 µm<br />

Sporangium of Saksenaea vasiformis.


Descriptions of Medical Fungi 131<br />

Scedosporium apiospermum/aurantiacum Complex<br />

Recent genetic studies have shown Scedosporium apiospermum to be a species complex<br />

and two species of medical importance have now been recognised: S. apiospermum<br />

and S. aurantiacum (Gilgado et al. 2005).<br />

Scedosporium apiospermum (Saccardo) Castellani and Chalmers<br />

Colonies are fast growing, greyish-white, suede-like to downy with a greyish-black reverse.<br />

Numerous single-celled, pale-brown, broadly clavate to ovoid conidia, 4-9 x 6-<br />

10 mm, rounded above with truncate bases are observed. Conidia are borne singly or<br />

in small groups on elongate, simple or branched conidiophores or laterally on hyphae.<br />

Conidial development can be described as annellidic, although the annellations (ringlike<br />

scars left at the apex of an annellide after conidial secession) are extremely difficult<br />

to see. Optimum temperature for growth is 30-37 O C. RG-2 organism.<br />

Ascocarp formation may be stimulated on cornmeal agar or other nutrient deficient<br />

media, however it should be noted that many isolates may fail to produce cleistothecia.<br />

Cleistothecia (non-ostiolate ascocarps) are yellow-brown to black, spherical, are mostly<br />

submerged in the agar and are composed of irregularly interwoven brown hyphae.<br />

When crushed cleistothecia release numerous, faintly brown, ellipsoidal ascospores,<br />

4-5 x 7- 9 µm in size. A Graphium synanamorph may also be present.<br />

The teleomorph is currently referred to as Pseudallescheria boydii, however as all<br />

species of Pseudallescheria have Scedosporium anamorphs, it is presumptive to use<br />

the teleomorph name to describe this fungus without seeing cleistothecia (ascocarps).<br />

Until the taxonomy of Pseudallescheria is resolved, it is recommended that laboratories<br />

use the anamorphic name Scedosporium apiospermum when describing this fungus.<br />

Scedosporium aurantiacum Gilgado et al.<br />

All isolates produce a light yellow diffusible pigment on PDA after a few days incubation.<br />

Conidiogenous cells and conidia are similar in shape and size to S. apiospermum,<br />

and the two can best be distinguished by genetic analysis. Conidiogenous cells arising<br />

from undifferentiated hyphae are cylindrical to slightly flask-shaped, producing slimy<br />

heads of one-celled , smooth-walled, subhyaline, obovoid or sub-cylindrical conidia.<br />

5-14 x 2-5 um. Erect synnemata (a Graphium synanamorph) may be present in some<br />

isolates, but the teleomorph is unknown. Optimum temperature for growth 37-40 O C,<br />

max 45 O C. RG-2 organism.<br />

S. apiospermum and S. aurantiacum appear to be common soil fungi capable of causing<br />

a spectrum of diseases similar in terms of variety and severity to those caused by<br />

Aspergillus collectively referred to as Pseudallescheriasis. The vast majority of infections<br />

are mycetomas, the remainder include infections of the eye, ear, central nervous<br />

system, internal organs and more commonly the lungs.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Domsch et al. (1980), McGinnis et al. (1982), Campbell and Smith (1982), Rippon<br />

(1988), de Hoog et al. (2000) and Gilgado et al. (2005).


132<br />

Descriptions of Medical Fungi<br />

Scedosporium apiospermum (Saccardo) Castellani and Chalmers<br />

Antifungal<br />

Culture and a cleistothecium of Pseudallescheria boydii.<br />

20 µm<br />

20 µm<br />

Conidiophores (annellides) and conidia of Scedosporium apiospermum.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Itraconazole 0.06-4 2 Amphotericin B 1-16 16<br />

Voriconazole 0.03-1 0.5 Posaconazole 0.5-2 1<br />

Good data available. McGinnis and Pasarell (1998), Espinel-Ingroff (2001, 2003),<br />

Espinel-Ingroff et al. (2001) and Cuenca-Estrella et al. (2006). MIC 90 s from the<br />

Australian Scedosporium Study.


Descriptions of Medical Fungi 133<br />

Scedosporium aurantiacum Gilgado et al.<br />

Culture reverse (PDA) of S. apiospermum (left) and S. aurantiacum (right) showing<br />

the production of a light yellow diffusible pigment that is typical of S. aurantiacum.<br />

Antifungal<br />

20 µm<br />

Conidiophores (annellides) and conidia of Scedosporium aurantiacum.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Itraconazole 0.25-2 1 Amphotericin B 2-16 16<br />

Voriconazole 0.03-0.5 0.25 Posaconazole 0.125-1 0.5<br />

Good data available. Australian Scedosporium Study.


134<br />

Descriptions of Medical Fungi<br />

Scedosporium prolificans (Hennebert & Desai) Gueho & de Hoog<br />

Synonym: Scedosporium inflatum Malloch & Salkin<br />

Colonies are rapid growing, flat, spreading, olive-grey to black and have a suede-like<br />

to downy surface texture. Conidia are borne in small groups on distinctive basally<br />

swollen, flask-shaped annellides, which occur singly or in clusters along the vegetative<br />

hyphae. Conidia are single-celled, hyaline to pale-brown, ovoid to pyriform, 2-5 x 3-13<br />

µm (average 3.4 x 5.3 µm), and have smooth thin walls. RG-2 organism.<br />

Key Features: dematiaceous hyphomycete with initial black pasty colony, basally<br />

swollen (inflated) annellides and no growth on media containing cycloheximide<br />

(actidione).<br />

For descriptions of species, keys to taxa and additional information see Malloch and<br />

Salkin (1984), Salkin et al. (1988), Rippon (1988), Wilson et al. (1990), Gueho and de<br />

Hoog (1991) and de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

Conidiophores (annellides) and conidia of Scedosporium prolificans.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Itraconazole 1-32 >8 Amphotericin B 1-16 >8<br />

Voriconazole 0.5-32 >8 Posaconazole >8 >8<br />

Good data available. McGinnis and Pasarell (1998), Espinel-Ingroff (2001, 2003),<br />

Espinel-Ingroff et al. (2001), Sabatelli et al. (2006), Cuenca-Estrella et al. (2006) and<br />

the Australian Scedosporium Study.


Descriptions of Medical Fungi 135<br />

Schizophyllum commune Fries<br />

Colonies on 2% malt extract agar are spreading, woolly, whitish to pale greyish-brown,<br />

soon forming macroscopically visible fruiting bodies. Although some isolates may take<br />

up to 12 weeks to form fruiting bodies. Fruit bodies are sessile, kidney-shaped, lobed<br />

with split gills on the lower side. Hyphae are hyaline, wide and have clamp connections<br />

(although many primary clinical isolates are monokaryotic and will therefore not<br />

produce clamp connections). Basidia bear 4 basidiospores on erect sterigmata. Basidiospores<br />

hyaline, smooth-walled, elongate with lateral scar at lower end, 6-7 x 2-3<br />

µm.<br />

Shizophyllum is a common bracket fungus on rotten wood, and is an occasional human<br />

pathogen, principally associated with sinusitis, allergic bronchopulmonary mycosis<br />

and as a contaminant from respiratory specimens. RG-1 organism.<br />

Note: many clinical isolates of S. commune are monokaryotic and therefore do not<br />

show clamp connections, therefore any white, rapidly growing, sterile isolate showing<br />

good growth at 37 O C with tolerance to benomyl, susceptibility to cycloheximide, and a<br />

pronounced odour should be suspected of being S. commune (Sigler et al., 1995).<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Rippon (1988), Sigler et al. (1995) and de Hoog et al. (2000).<br />

Basidiocarps of Schizophyllum commune on malt extract agar.


136<br />

Descriptions of Medical Fungi<br />

Scopulariopsis Bain<br />

Colonies are fast growing, varying in colour from white, cream, grey, buff to brown,<br />

black, but are predominantly light brown. Microscopic morphology shows chains of<br />

single-celled conidia produced in basipetal succession from by a specialised conidiogenous<br />

cell called an annellide. Once again, the term basocatenate can be used<br />

to describe such chains of conidia where the youngest conidium is at the basal end of<br />

the chain. In Scopulariopsis, annellides may be solitary, in groups, or organised into<br />

a distinct penicillus. Conidia are globose to pyriform, usually truncate, with a rounded<br />

distal portion, smooth to rough, and hyaline to brown in colour.<br />

Most members of the genus Scopulariopsis are soil fungi, however a few, in particular<br />

S. brevicaulis, have been reported as causative agents of onychomycosis and hyalohyphomycosis.<br />

RG-2 for species isolated from humans.<br />

Key Features: hyphomycete, conidia often shaped like light globes, basocatenate<br />

arising from annellides.<br />

For descriptions of species, keys to taxa and additional information see Morton and<br />

Smith (1963), Domsch et al. (1980), McGinnis (1980), Rippon (1988), Samson et al.<br />

(1995) and de Hoog et al. (2000).<br />

Antifungal<br />

10 µm<br />

Conidiophores (annellides) and conidia of Scopulariopsis brevicaulis.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 2-16 Itraconazole 32 Voriconazole 2-8<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis and Pasarell (1998) and WCH in-house data.


Descriptions of Medical Fungi 137<br />

Sepedonium Link ex Greville<br />

Colonies are moderately fast growing, usually white to golden yellow, suede-like to<br />

downy, becoming fluffy with age. Conidiophores are hyaline and non-specialised, resembling<br />

short branches of the vegetative hyphae. Conidia are terminal, solitary, or<br />

in clusters, one-celled, globose to ovoid, 7 to 17 µm, hyaline to amber, smooth to verrucose<br />

and usually with a thick wall.<br />

The microscopic morphology of Sepedonium isolates resembles that of Histoplasma<br />

capsulatum. Therefore, positive identification of the latter, requires conversion of the<br />

mould form to the yeast phase by growth at 37 O C on enriched media or by exoantigen<br />

test. RG-1 organism.<br />

Key Features: hyphomycete, producing large, thick-walled, one-celled, verrucose,<br />

globose, terminal macroconidia from non-specialised conidiophores, resembling Histoplasma<br />

capsulatum.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980) and Rippon (1988).<br />

Conidia of Sepedonium.<br />

15 µm


138<br />

Descriptions of Medical Fungi<br />

Sporothrix schenckii Hektoen & Perkins<br />

Colonies (SDA) at 25 O C, are slow growing, moist and glabrous, with a wrinkled and<br />

folded surface. Some strains may produce short aerial hyphae and pigmentation may<br />

vary from white to cream to black. Conidiophores arise at right angles from thin septate<br />

hyphae and are usually solitary, erect and tapered toward the apex. Conidia are<br />

formed in clusters on tiny denticles by sympodial proliferation at the apex of the conidiophore,<br />

their arrangement often suggestive of a flower. As the culture ages, conidia<br />

are subsequently formed singly along the sides of both conidiophores and undifferentiated<br />

hyphae. Conidia are ovoid or elongated, 3-6 x 2-3 µm, hyaline, one-celled and<br />

smooth-walled. In some isolates, solitary, darkly-pigmented, thick-walled, one-celled,<br />

obovate to angular conidia may also be observed along the hyphae.<br />

On brain heart infusion agar containing blood at 37 O C, colonies are glabrous, white to<br />

greyish-yellow and yeast-like consisting of spherical or oval budding yeast cells.<br />

Sporothrix schenckii is a dimorphic fungus and has a world-wide distribution, particularly<br />

in tropical and temperate regions. It is commonly found in soil and on decaying<br />

vegetation and is a well known pathogen of humans and animals. Sporotrichosis is<br />

primarily a chronic mycotic infection of the cutaneous or subcutaneous tissues and adjacent<br />

lymphatics characterised by nodular lesions which may suppurate and ulcerate.<br />

Infections are caused by the traumatic implantation of the fungus into the skin, or very<br />

rarely, by inhalation into the lungs. Secondary spread to articular surfaces, bone and<br />

muscle is not infrequent, and the infection may also occasionally involve the central<br />

nervous system, lungs or genitourinary tract. RG-2 organism.<br />

Key Features: hyphomycete characterised by thermal dimorphism and clusters of<br />

ovoid, denticulate conidia produced sympodially on short conidiophores.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Domsch et al. (1980), de Hoog et al. (1985), Rippon (1988) and de Hoog et al.<br />

(2000).<br />

10 µm<br />

Periodic Acid-Schiff (PAS) stained tissue section showing budding<br />

yeast-like cells of S. schenckii.


Descriptions of Medical Fungi 139<br />

Antifungal<br />

Sporothrix schenckii Hektoen & Perkins<br />

10 µm<br />

Culture on SDA at 25 O C and budding yeast cells in BHI at 37 O C.<br />

10 µm<br />

Conidiophores and conidia of Sporothrix schenckii on SDA at 25 O C.<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Fluconazole 32->64 >64 Amphotericin B 0.06->16 >16<br />

Itraconazole 0.03->16 0.5 (4) Flucytosine 4->64 >64<br />

Posaconazole 0.125-4 2 Caspofungin 1->8 nd<br />

Voriconazole 0.125->16 4 (16) Anidulafungin 0.25->8 nd<br />

Limited data, antifungal susceptibility testing of individual strains is recommended.<br />

McGinnis et al. (2001), Espinel-Ingroff et al. (2001), Espinel-Ingroff (2003), Gonzales<br />

et al. (2005) and Alvarado-Ramirez and Torres-Rodriguez (2007). (nd = not done).


140<br />

Descriptions of Medical Fungi<br />

Stemphylium Wallroth<br />

Colonies are rapid growing, brown to olivaceous-black or greyish and suede-like to<br />

floccose. Microscopically, solitary, darkly pigmented, terminal, multicellular conidia<br />

(dictyoconidia) are formed on a distinctive conidiophore with a darker terminal swelling.<br />

Note: the conidiophore proliferates percurrently through the scar where the terminal<br />

conidium (poroconidium) was formed. Conidia are pale to mid-brown, oblong,<br />

rounded at the ends, ellipsoidal, obclavate or subspherical and are smooth or in part<br />

verrucose. Stemphylium should not be confused with Ulocladium which produces similar<br />

dictyoconidia from a sympodial conidiophore, not from a percurrent conidiogenous<br />

cell as in Stemphylium. RG-1 organism.<br />

Key Features: dematiaceous hyphomycete producing darkly pigmented, dictyoconidia<br />

from the swollen end of a percurrent conidiophore.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971 and<br />

1976), Rippon (1988) and de Hoog et al. (2000).<br />

20 µm<br />

Conidiophores and conidia of Stemphylium.


Descriptions of Medical Fungi 141<br />

Syncephalastrum Schröter<br />

The genus Syncephalastrum is characterised by the formation of cylindrical merosporangia<br />

on a terminal swelling of the sporangiophore. Sporangiospores are arranged<br />

in a single row within the merosporangia. Syncephalastrum racemosum is the type<br />

species of the genus and a potential human pathogen; however, well-documented<br />

cases are lacking. It is found mainly from soil and dung in tropical and subtropical regions.<br />

It can also be a difficult laboratory aerial contaminant. The sporangiophore and<br />

merosporangia of Syncephalastrum species may also be mistaken for an Aspergillus<br />

species, if the isolate is not looked at carefully.<br />

Colonies are very fast growing, cottony to fluffy, white to light grey, becoming dark<br />

grey with the development of sporangia. Sporangiophores are erect, stolon-like, often<br />

producing adventitious rhizoids, and show sympodial branching (racemose branching)<br />

producing curved lateral branches. The main stalk and branches form terminal, globose<br />

to ovoid vesicles which bear finger-like merosporangia directly over their entire<br />

surface. At maturity, merosporangia are thin-walled, evanescent and contain 5-10(18)<br />

globose to ovoid, smooth-walled sporangiospores (merospores). Optimum growth<br />

temperature 20-40 O C. RG-2 organism.<br />

Key Features: zygomycete producing sympodially branching sporangiophores with<br />

terminal vesicles bearing merosporangia.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980), Onions et al. (1981), Rippon (1988), Samson et al. (1995),<br />

Hoog et al. (2000) and Ellis (2005b).<br />

30 µm<br />

10 µm<br />

Terminal vesicle, merosporangia and merospores of S. racemosum.


142<br />

Descriptions of Medical Fungi<br />

Trichoderma Persoon ex Grey<br />

Colonies are fast growing, at first white and downy, later developing yellowish-green<br />

to deep green compact tufts, often only in small areas or in concentric ring-like zones<br />

on the agar surface. Conidiophores are repeatedly branched, irregularly verticillate,<br />

bearing clusters of divergent, often irregularly bent, flask-shaped phialides. Conidia<br />

are mostly green, sometimes hyaline, with smooth or rough walls and are formed in<br />

slimy conidial heads (gloiospora) clustered at the tips of the phialides.<br />

Trichoderma is a very common genus especially in soil and decaying wood. Gliocladium<br />

(with strongly convergent phialides) and Verticillium (with straight and moderately<br />

divergent phialides) are closely related genera. Trichoderma is an RG-1 organism.<br />

Key Features: hyphomycete with repeatedly branched conidiophores bearing clusters<br />

of divergent, flask-shaped phialides.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980), Rippon (1988), Samson et al. (1995), de Hoog et al. (2000).<br />

Antifungal<br />

20 µm<br />

Phialides and conidia of Trichoderma harzianum.<br />

MIC µg/mL MIC µg/mL MIC µg/mL<br />

Antifungal Antifungal<br />

Range Range Range<br />

Amphotericin B 0.5-2 Itraconazole 2-16 Voriconazole 0.25-2<br />

Very limited data, antifungal susceptibility testing of individual strains is recommended.<br />

Espinel-Ingroff (2001) and WCH in-house data.


Descriptions of Medical Fungi 143<br />

Trichophyton Malmsten<br />

The genus Trichophyton is characterised by the development of both smooth-walled<br />

macro- and microconidia. Macroconidia are mostly borne laterally directly on the hyphae<br />

or on short pedicels, and are thin- or thick-walled, clavate to fusiform, and range<br />

from 4-8 x 8-50 mm in size. Macroconidia are few or absent in many species. Microconidia<br />

are spherical, pyriform to clavate or of irregular shape and range from 2-3 x 2-4<br />

mm in size. The presence of microconidia distinguishes this genus from Epidermophyton<br />

and the smooth-walled, mostly sessile macroconidia separate it from Microsporum.<br />

Twenty species have been recognised, however only the more common species are<br />

included in these descriptions.<br />

In practice, two groups may be recognised on direct microscopy:<br />

1. Those species that usually produce microconidia, macroconidia may or may not be<br />

present i.e. T. rubrum, T. interdigitale, T. mentagrophytes, T. equinum, T. erinacei,<br />

T. tonsurans, T. terrestre and to a lesser extent T. verrucosum, which may produce<br />

conidia on some media; and<br />

2. Those species that usually do not produce conidia. Chlamydospores or other<br />

hyphal structures may be present, but microscopy is generally non-diagnostic; i.e.<br />

T. verrucosum, T. violaceum, T. concentricum, T. schoenleinii and T. soudanense.<br />

Many laboratories seem to have difficulty in distinguishing between species of Trichophyton,<br />

especially isolates of T. rubrum, T. interdigitale, T. mentagrophytes and T.<br />

tonsurans. Basically, the laboratories which consistently identify these fungi correctly<br />

do more work and use additional media and/or confirmatory tests. However, it must<br />

be stressed that no one single test is infallible, dermatophyte species are very variable<br />

organisms and many characteristics either overlap or are inconsistent.<br />

The Mycology Unit at the Adelaide Women’s and Children’s Hospital uses a dermatophyte<br />

identification scheme, devised by the late Geraldine Kaminski, comprising 6<br />

different media to help identify and differentiate the various species and strains of<br />

Trichophyton. The media in this scheme are Littman Oxgall agar, Lactritmel agar,<br />

Sabouraud’s agar with 5% NaCl, 1% Peptone agar, Trichophyton agar No. 1, and hydrolysis<br />

of urea (see appendix for details).<br />

Note: species concepts in dermatophytes are currently in a state of flux. Recent molecular<br />

studies have shown that many species appear to be clonal and that there is<br />

little correlation between “genetic” and “phenotypic” species (Graser et al. 2006). The<br />

descriptions and species concepts provided in this publication are based on traditional<br />

morphological criteria which may not correspond to molecular identification results.<br />

For description of species, keys to taxa and additional information see Rebell and<br />

Taplin (1970), Ajello (1972), Vanbreusegham et al. (1978), Rippon (1988), McGinnis<br />

(1980), Domsch et al. (1980), Kane et al. (1997) and de Hoog et al. (2000).<br />

Antifungal<br />

MIC µg/mL<br />

MIC µg/mL<br />

Range MIC90 Antifungal Range MIC90 Griseofulvin 0.06-4 1-2 Amphotericin B 0.03-16 0.5-1<br />

Itraconazole 0.01-8 0.25-0.5 Fluconazole 0.06->64 32<br />

Terbinafine 0.01-16 0.06 Voriconazole 0.007-8 0.25<br />

Fernandez-Torres et al. (2001), Sabatelli et al. (2006), Santos and Hamdan (2006).


144<br />

Descriptions of Medical Fungi<br />

Trichophyton ajelloi (Vanbreuseghem) Ajello<br />

Teleomorph: Arthroderma uncinatum Dawson and Gentles<br />

Colonies are usually flat, powdery, cream to tan to orange-tan in colour, with a blackish-purple<br />

submerged fringe and reverse. Macroconidia are numerous, smooth, thickwalled,<br />

elongate, cigar-shaped, 29-65 x 5-10 µm, and multiseptate with up to 9 or 10<br />

septa. Microconidia are usually absent, but when present are ovate to pyriform in<br />

shape. RG-1 organism.<br />

Trichophyton ajelloi is a geophilic fungus with a world-wide distribution which may occur<br />

as a saprophytic contaminant on humans and animals. Infections in man and animals<br />

doubtful. Not known to invade hair in vivo, but produces hair perforations in vitro.<br />

Key Features: culture characteristics, macroconidial morphology, urease positive and<br />

good growth on Sabouraud’s 5% salt agar.<br />

20 µm<br />

Culture and macroconidia of Trichophyton ajelloi.


Descriptions of Medical Fungi 145<br />

Trichophyton concentricum Blanchard<br />

Teleomorph: Arthroderma benhamiae Ajello & Chang.<br />

Colonies (SDA) are slow growing, raised and folded, glabrous becoming suede-like,<br />

mostly white to cream-coloured, but sometimes orange-brown-coloured, often deeply<br />

folded into the agar which may produce splitting of the medium in some cultures. Reverse<br />

is buff to yellow-brown to brown in colour. Cultures consist of broad, muchbranched,<br />

irregular, often segmented, septate hyphae which may have “antler” tips<br />

resembling T. schoenleinii. Chlamydospores are often present in older cultures. Microconidia<br />

and macroconidia are not usually produced, although some isolates will<br />

produce occasional clavate to pyriform microconidia. Note: hyphal segments may<br />

artificially resemble macroconidia. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Small, heaped and folded, blue-grey, suede to glabrous colonies<br />

with no reverse or diffusible pigment.<br />

Lactritmel Agar: Colonies tend to be flatter, dull-white, suede-like, almost glabrous<br />

with a yellow-brown reverse pigment. Microscopic morphology is similar to that described<br />

above, however occasional clavate to pyriform microconidia may be present.<br />

Note: occasional, small, slender, smooth thin-walled macroconidia with 2-3 septa have<br />

been reported on specialised media like lactritmel agar, bean pod agar and hay infusion<br />

agar.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Small, stunted, heaped and folded,<br />

cream to buff, glabrous colonies with no reverse pigment.<br />

1% Peptone Agar: Flat, white, suede-like colony with a pale yellow-brown reverse.<br />

Hydrolysis of Urea: Negative after 7 days<br />

Vitamin Free Agar (Trichophyton Agar No.1): Growth occurs on vitamin free agar<br />

(T1) but is usually slightly better on media containing thiamine i.e. T3 = T1 + thiamine<br />

and inositol, and T4 = T1 + thiamine. The slight enhancement of growth in the presence<br />

of thiamine helps to distinguish T. concentricum from T. schoenleinii, although<br />

this does not occur in all strains.<br />

Hair Perforation Test: Negative at 28 days.<br />

Trichophyton concentricum is an anthropophilic fungus which causes chronic widespread<br />

non-inflammatory tinea corporis known as tinea imbricata because of the concentric<br />

rings of scaling it produces. It is not known to invade hair. Infections among<br />

Europeans are rare. Distribution is restricted to the Pacific Islands of Oceania, South<br />

East Asia and Central and South America.<br />

Key Features: hyphomycete (dermatophyte), clinical disease, geographical distribution<br />

and culture characteristics.


146<br />

Descriptions of Medical Fungi<br />

Trichophyton concentricum Blanchard<br />

20 µm<br />

T. concentricum on mycobiotic agar showing a typical slow<br />

growing, heaped and folded, glabrous to suede like colony.<br />

Microscopic morphology of T. concentricum showing the formation<br />

of typical “balloon-shaped” chlamydospores. Note: microconidia<br />

and macroconidia are usually not produced.


Descriptions of Medical Fungi 147<br />

Trichophyton equinum (Matruchot & Dassonville) Gedoelst<br />

Teleomorph: Arthroderma vanbreuseghemii Takashio<br />

Colonies (SDA) are usually flat, but some may develop gentle folds or radial grooves,<br />

white to buff in colour, suede-like to downy in texture, and are similar to T. mentagrophytes.<br />

Cultures usually have a deep-yellow submerged fringe and reverse which<br />

later becomes dark red in the centre. Microscopically, abundant microconidia which<br />

may be clavate to pyriform and sessile or spherical and stalked are formed laterally<br />

along the hyphae. Macroconidia are only rarely produced, but when present are clavate,<br />

smooth, thin-walled and of variable size. Occasional nodular organs may be<br />

present and the microconidia often undergo a transformation to produce abundant<br />

chlamydospores in old cultures. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Compact, raised velvety white surface with yellowish reverse<br />

and diffusing yellow pigment.<br />

Lactritmel Agar: Flat spreading, white to cream-coloured, powdery to granular surface<br />

with a central downy papilla, and deep brownish red reverse. Microscopic morphology<br />

as described above for the primary culture.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: An extremely stunted, slow growing dark<br />

brown colony with a few submerged brown hyphae.<br />

1% Peptone Agar: Flat white to cream, suede-like surface with raised white downy<br />

centre and pale yellow reverse.<br />

Hydrolysis of Urea: Positive in 4-5 days.<br />

Nutritional Tests on Trichophyton Agars: Most strains require nicotinic acid (Fig. 1)<br />

for growth except those from Australia and New Zealand, which are autotrophic (Fig.<br />

2). T1 = vitamin free agar, T5 = vitamin free + nicotinic acid agar.<br />

Fig. 1. Fig. 2.<br />

Hair Perforation Test: Negative; but positive for the autotrophicum strains.<br />

Key Features: microscopic morphology, culture characteristics, nicotinic acid requirement<br />

and clinical lesions in horses.


148<br />

Descriptions of Medical Fungi<br />

Trichophyton equinum (Matruchot & Dassonville) Gedoelst<br />

Trichophyton equinum is a zoophilic fungus causing ringworm in horses and rare infections<br />

in humans. It has a world-wide distribution except for the autotrophicum strain<br />

which is restricted to Australia and New Zealand. Invaded hairs show an ectothrix<br />

infection but do not fluoresce under Wood’s ultra-violet light.<br />

20 µm<br />

Culture, microconidia, macroconidia and nodular organs of T. equinum.


Descriptions of Medical Fungi 149<br />

Trichophyton erinacei (Smith & Marples) Quaife<br />

Teleomorph: Arthroderma benhamiae Ajello & Chang.<br />

Colonies (SDA) are white, flat, powdery, sometimes downy to fluffy with a brilliant lemon<br />

yellow reverse. Numerous large clavate microconidia are borne on the sides of<br />

hyphae. Macroconidia are smooth-walled, two- to six-celled, clavate, variable in size,<br />

and may have terminal appendages. Macroconidia are much shorter than those seen<br />

in T. mentagrophytes. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: White, downy colony with yellowish-green diffusible pigment.<br />

Lactritmel Agar: White suede-like to powdery colony with brilliant yellow reverse.<br />

Numerous large slender clavate microconidia.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: White folded suede-like to powdery<br />

colony with no reverse pigment.<br />

1% Peptone Agar: White, suede-like to powdery colony with pale yellow reverse.<br />

Hydrolysis of Urea: Negative at 7 days.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. Colonies are white suede-like to powdery with no reverse<br />

pigment.<br />

Hair Perforation Test: Positive<br />

Trichophyton erinacei is a zoophilic fungus associated with hedgehogs and the epidermal<br />

mites which they often harbour. Human infections occur most frequently on the<br />

exposed parts of the body, but tinea of the scalp and nails can also occur. Invaded<br />

hairs show an ectothrix infection but do not fluoresce under Wood’s ultra-violet light.<br />

The distribution of this fungus is New Zealand and Europe.<br />

Positive “in vitro” hair perforation test.


150<br />

Descriptions of Medical Fungi<br />

Trichophyton erinacei (Smith & Marples) Quaife<br />

Key Features: culture characteristics, microscopic morphology, geographical<br />

distributions and negative urease test.<br />

20 µm<br />

Culture, microconidia and macroconidia of Trichophyton erinacei.<br />

Trichophyton erinacei is generally distinguished from T. mentagrophytes by (a) its<br />

microscopic morphology showing numerous large slender clavate microconidia borne<br />

on the sides of hyphae and its smooth, thin-walled clavate macroconidia; (b) its brilliant<br />

lemon yellow reverse pigment on plain Sabouraud’s agar and Lactritmel agar; (c) its<br />

lack of reverse pigment on Sabouraud’s salt agar; and (d) its negative hydrolysis of<br />

urea.


Descriptions of Medical Fungi 151<br />

Teleomorph: Arthroderma vanbreuseghemii Takashio<br />

Colonies (SDA) are usually flat, white to cream in colour with a powdery to suede-like<br />

surface and yellowish and pinkish brown reverse pigment, often becoming a darker<br />

red-brown with age. Numerous subspherical to pyriform microconidia, occasional spiral<br />

hyphae and spherical chlamydospores are present, the latter being more abundant<br />

in older cultures. Occasional slender, clavate, smooth-walled, multiseptate macroconidia<br />

are also present in some cultures. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: raised white downy colony with no reverse pigment.<br />

Lactritmel Agar: Macroscopic and microscopic features as described for the primary<br />

culture.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Heaped and folded, buff-coloured suedelike<br />

surface with a dark reddish-brown submerged fringe and brown reverse.<br />

1% Peptone Agar: Flat, white to cream, suede-like surface with raised white downy<br />

centre. No reverse pigment.<br />

Hydrolysis of Urea: Positive within 5 days.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements, flat cream powdery surface with central downy tuft. Reverse<br />

pale pinkish-brown.<br />

Hair Perforation Test: Positive.<br />

Trichophyton interdigitale Priestley<br />

Key Features: culture characteristics, microscopic morphology and in vitro perforation<br />

of human hair.<br />

Trichophyton interdigitale can be distinguished from T. rubrum and T. mentagrophytes<br />

by (a) its culture characteristics and microscopic morphology on Sabouraud’s dextrose<br />

agar and/or lactritmel agar; (b) its growth and colony morphology on Sabouraud’s salt<br />

agar (colonies of T. interdigitale and T. mentagrophytes unlike T. rubrum, grow very<br />

well on this medium and usually produce a distinctive dark reddish-brown reverse pigment);<br />

(c) a positive urease test (within 7 days), a positive hair perforation test and the<br />

production of a yellow-brown to pinkish-brown reverse pigment on pigment stimulation<br />

media like lactritmel and Trichophyton No.1 agars; and (d) on 1% peptone agar<br />

T. interdigitale has a suede-like to downy surface whereas T. mentagrophytes has a<br />

characteristic granular appearance.<br />

Trichophyton interdigitale is an anthropophilic fungus which is a common cause of<br />

tinea pedis, particularly the vesicular type, tinea corporis, and sometimes superficial<br />

nail plate invasion. It is not known to invade hair in vivo but produces hair perforations<br />

in vitro. Distribution is world-wide.


152<br />

Descriptions of Medical Fungi<br />

20 µm<br />

Trichophyton interdigitale Priestley<br />

20 µm<br />

Culture, microconidia, macroconidia, chlamydospores and spiral hyphae in<br />

Trichophyton interdigitale.


Descriptions of Medical Fungi 153<br />

Trichophyton interdigitale var. nodulare<br />

Supplementary description for Trichophyton interdigitale var. nodulare, a dysgonic variant<br />

of T. interdigitale with distinctive bright yellow to apricot-coloured colonies with a<br />

suede-like to powdery surface and a bright yellow-brown to orange reverse. On primary<br />

isolation, colonies are often glabrous with minimal surface mycelium. Microscopically<br />

characteristic “nodular organs” are observed in the vegetative hyphae. Usually,<br />

no conidia are seen but some isolates, especially with subculture, may produce subspherical<br />

to pyriform microconidia similar to those of T. interdigitale. RG-2 organism.<br />

T. interdigitale var. nodulare is an unusual cause of tinea pedis. It has a world-wide distribution.<br />

It is not known to invade hair in vivo, but produces hair perforations in vitro.<br />

20 µm<br />

Culture and “nodular organs” T. interdigitale var. nodulare.


154<br />

Descriptions of Medical Fungi<br />

Trichophyton mentagrophytes (Robin) Blanchard<br />

Teleomorph: Arthroderma simii Stockdale et al.<br />

Colonies (SDA) are generally flat, white to cream in colour, with a powdery to granular<br />

surface. Some cultures show central folding or develop raised central tufts or pleomorphic<br />

suede-like to downy areas. Reverse pigmentation is usually a yellow-brown to<br />

reddish-brown colour. Numerous single-celled microconidia are formed, often in dense<br />

clusters. Microconidia are hyaline, smooth-walled, and are predominantly spherical to<br />

subspherical in shape, however occasional clavate to pyriform forms may occur. Varying<br />

numbers of spherical chlamydospores, spiral hyphae and smooth, thin-walled, clavate-shaped,<br />

multi-celled macroconidia may also be present. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Raised greyish-white, suede-like to downy colony. Some cultures<br />

may show a diffusible yellow to brown pigment.<br />

Lactritmel Agar: Cultures are flat, white to cream in colour, with a powdery to granular<br />

surface. Some cultures develop a raised central tuft or pleomorphic downy areas. Reverse<br />

pigmentation is yellow-brown to pinkish-brown to red-brown. Microscopic morphology<br />

similar to that described above, with predominantly spherical microconidia,<br />

often forming in dense clusters and varying numbers of spherical chlamydospores,<br />

spiral hyphae and smooth, thin-walled, clavate, multiseptate macroconidia.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Cultures are heaped and folded, buff to<br />

brown in colour, with a suede-like surface texture and characteristically have a very<br />

dark reddish-brown submerged peripheral fringe and reverse pigmentation.<br />

1% Peptone Agar: Flat, cream-coloured, powdery to granular colony with no reverse<br />

pigment.<br />

Hydrolysis of Urea: Positive within 7 days (usually 3 to 5 days).<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. Cultures are flat, cream-coloured, with a powdery to suedelike<br />

surface, and have a reddish-brown reverse pigmentation.<br />

Hair Perforation Test: Positive within 14 days.<br />

Key Features: culture characteristics, microscopic morphology and clinical disease<br />

with known animal contacts. T. mentagrophytes can be distinguished from T. interdigitale<br />

by (a) its granular appearance on 1% Peptone agar, (b) its microscopic morphology<br />

of more spherical microconidia and generally greater numbers of macroconidia<br />

and (c) a yellow to brown diffusible pigment is often seen on Littman Oxgall agar.<br />

T. mentagrophytes is the zoophilic form of T. mentagrophytes with a world-wide distribution<br />

and a wide range of animal hosts including mice, guinea-pigs, kangaroos, cats,<br />

horses, sheep and rabbits. Produces inflammatory skin or scalp lesions in humans,<br />

particularly in rural workers. Kerion of the scalp and beard may occur. Invaded hairs<br />

show an ectothrix infection but do not fluoresce under Wood’s ultra-violet light.


Descriptions of Medical Fungi 155<br />

Trichophyton mentagrophytes (Robin) Blanchard<br />

20 µm 20 µm<br />

20 µm<br />

Cultures, microconidia, macroconidia, chlamydospores and spiral hyphae in<br />

Trichophyton mentagrophytes.


156<br />

Descriptions of Medical Fungi<br />

Trichophyton mentagrophytes var. quinckeanum (Zopf) MacLeod & Muende<br />

Colonies (SDA) are flat or slightly raised and folded, white to cream, suede-like in<br />

texture with a pale yellow-brown to pinkish brown reverse. A characteristic pungent<br />

“mousy” odour may be present. Numerous microconidia, predominantly slender clavate<br />

when young, are borne laterally along the sides of hyphae. With age the microconidia<br />

become broader and pyriform, and some subspherical forms are present. Occasional<br />

to moderate numbers of smooth-walled, multiseptate, clavate macroconidia<br />

may be present. RG-2 organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Raised, dome-like bluish-grey, suede-like colony with a narrow<br />

flat, greyish-white, suede-like border. No diffusible or reverse pigment should be<br />

present.<br />

Lactritmel Agar: Flat, white to cream, suede-like to powdery colony with either no<br />

reverse pigment or a pale yellow-brown to pinkish-brown reverse. Numerous slender<br />

clavate to pyriform (depending on age of sub-culture) microconidia and occasional to<br />

moderate numbers of smooth, thin-walled, clavate macroconidia are present.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Heaped up and much folded white<br />

suede-like colony with very pale yellow-brown reverse. No submerged fringe.<br />

1% Peptone Agar: Raised white suede-like to downy colony with no reverse<br />

pigment.<br />

Hydrolysis of Urea: Positive within 7 days (usually very rapid 2-3 days).<br />

Vitamin Free Agar (Trichophyton Agar No.1): Flat, white to cream, suede-like<br />

colony with either no reverse pigment or a pale yellow-brown reverse. i.e. no special<br />

nutritional requirements.<br />

Hair Perforation Test: Positive in 7 to 10 days.<br />

Key Features: culture characteristics, microscopic morphology, contact with mice,<br />

odour and rapid urease test.<br />

T. mentagrophytes var. quinckeanum may be distinguished from T. mentagrophytes by<br />

(a) its characteristic culture appearance on Littman Oxgall agar (i.e. raised, dome-like,<br />

bluish-grey suede-like colony with a narrow flat, greyish-white, suede-like border and<br />

no diffusible or reverse pigment); and on Sabouraud’s salt agar (typically heaped and<br />

folded white suede-like colony, but with no distinctive dark reddish-brown submerged<br />

fringe and reverse pigment as seen in T. mentagrophytes); (b) microscopic morphology<br />

showing numerous slender clavate with some pyriform microconidia and moderate<br />

numbers of smooth thin-walled, clavate macroconidia; (c) a rapid urease test, usually<br />

within 2 to 3 days; and (d) cultures often have a characteristic pungent “mousy”<br />

odour.


Descriptions of Medical Fungi 157<br />

Trichophyton mentagrophytes var. quinckeanum (Zopf) MacLeod & Muende<br />

Trichophyton mentagrophytes var. quinckeanum causes “mouse favus” on mice, and<br />

this is seen as thick, yellow, saucer-shaped crusted lesions up to 1 cm in diameter<br />

called scutula. Invaded hairs are rarely seen but they may show either ectothrix or<br />

endothrix infection. Infected human hairs do not fluoresce under Wood’s ultra-violet<br />

light, but very occasional hairs from experimental lesions in guinea pigs may show a<br />

pale yellow fluorescence. The geographical distribution of this dermatophyte is difficult<br />

to establish, but it is probably world-wide. It is often associated with mice plagues in<br />

the Australian Wheat Belt.<br />

20 µm<br />

Culture, microconidia and macroconidia of T. mentagrophytes var.<br />

quinckeanum.


158<br />

Descriptions of Medical Fungi<br />

Trichophyton rubrum (Castellani) Semon<br />

Many strains and varieties of T. rubrum have been described and opinion differs between<br />

mycologists as to the exact validity of many of these. For practical purposes we<br />

will distinguish two types: T. rubrum downy type and T. rubrum granular type.<br />

Microscopically, the downy type is characterised by the production of scanty to moderate<br />

numbers of slender clavate microconidia and no macroconidia. It frequently causes<br />

chronic infections of skin and nails. Granulomatous lesions may sometimes occur.<br />

Microscopically, the granular type is characterised by the production of moderate to<br />

abundant numbers of clavate to pyriform microconidia and moderate to abundant numbers<br />

of thin-walled, cigar-shaped macroconidia. The macroconidia may or may not<br />

have terminal appendages.<br />

Trichophyton rubrum granular strain is a frequent cause of tinea corporis in South East<br />

Asia and in Aborigines living in the Northern Territory of Australia. However, since the<br />

Vietnam War, it has been spread throughout the world, especially to those countries<br />

with returning troops or to those receiving refugees, where it has often been described<br />

as a new species. The granular strain of T. rubrum represents the parent strain of T.<br />

rubrum downy type; the latter evolved by establishing a niche in feet (tinea pedis) when<br />

the former was imported into Europe and North America at the beginning of the 20th<br />

century. It should be stressed that intermediate strains between the two types do occur<br />

and that many culture and morphological characteristics overlap.<br />

Trichophyton rubrum typical downy strain<br />

Colonies (SDA) are flat to slightly raised, white to cream, suede-like to downy, with a<br />

yellow-brown to wine-red reverse. Most cultures show scanty to moderate numbers of<br />

slender clavate to pyriform microconidia. Macroconidia are usually absent, however<br />

closterospore-like projections may be present in some mounts. Note: on primary isolation<br />

some cultures may lack reverse pigmentation and fail to produce microconidia.<br />

These will need to be subcultured onto media like Lactritmel agar or potato dextrose<br />

agar which stimulate pigmentation and sporulation. If sporulation still fails subculture<br />

the fungus onto Trichophyton Agar No.1. RG-2 organism.<br />

Culture of Trichophyton rubrum downy strain.


Descriptions of Medical Fungi 159<br />

Trichophyton rubrum (Castellani) Semon<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Raised, greyish-white, suede-like to downy colony with no reverse<br />

pigment. Some cultures may have showed a faint greenish-yellow diffusible<br />

pigment.<br />

Lactritmel Agar: Flat, white, downy colonies with a deep wine-red reverse pigment.<br />

Microscopically, cultures show the typical downy type morphology of pyriform to slender<br />

clavate microconidia.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Very stunted, white downy colony with a<br />

pale yellow-brown reverse pigment.<br />

1% Peptone Agar: Flat, white to cream, downy colony often with a raised centre. No<br />

reverse pigment produced.<br />

Hydrolysis of Urea: Negative at 7 days.<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

vitamin requirements. Colonies are flat, white to cream, suede-like to downy with a<br />

deep wine-red reverse pigment.<br />

Hair Perforation Test: Negative at 28 days.<br />

Key Features: culture characteristics, microscopic morphology and failure to perforate<br />

hair “in vitro”.<br />

20 µm<br />

Typical slender clavate microconidia of Trichophyton rubrum downy type.


160<br />

Descriptions of Medical Fungi<br />

Colonies (SDA) are flat to slightly raised, white to cream, suede-like with a pinkish-red<br />

reverse. Microscopically, most cultures have numerous clavate to pyriform microconidia<br />

and moderate numbers of smooth, thin-walled multiseptate, slender cylindrical<br />

macroconidia. Older cultures may show numerous chlamydospores with few clavate<br />

to pyriform microconidia.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Raised, greyish, suede-like colonies with some radial folding<br />

and a greenish-yellow diffusible pigment.<br />

Lactritmel Agar: Flat, white to rose pink, suede-like to granular colonies with a pinkish<br />

to wine-red reverse. Numerous broad clavate to pyriform microconidia and moderate<br />

numbers of smooth, thin-walled, slender cylindrical macroconidia are present. A few<br />

chlamydospores may be present in older cultures.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: A very stunted, heaped and folded,<br />

glabrous, cream thallus, later developing a dark red central spot. Reverse is a brownishyellow<br />

colour.<br />

1% Peptone Agar: Flat, white to cream, glabrous to suede-like colony with no reverse<br />

pigment.<br />

Hydrolysis of Urea: Positive at 7 days<br />

Vitamin Free Agar (Trichophyton Agar No.1): Good growth indicating no special<br />

nutritional requirements. White to cream suede-like colonies with a pinkish-red to<br />

wine-red reverse.<br />

Hair Perforation Test: Positive.<br />

Trichophyton rubrum granular type<br />

Key Features: culture characteristics and microscopic morphology.<br />

Culture of Trichophyton rubrum granular strain.


Descriptions of Medical Fungi 161<br />

20 µm<br />

Trichophyton rubrum granular type<br />

20 µm<br />

Macroconidia and microconidia of Trichophyton rubrum granular type.


162<br />

Descriptions of Medical Fungi<br />

Trichophyton schoenleinii (Lebert) Langeron & Milochevitch<br />

Colonies (SDA) are slow growing, waxy or suede-like with a deeply folded honeycomb-like<br />

thallus and some sub-surface growth. The thallus is cream-coloured to yellow<br />

to orange brown. Cultures are difficult to maintain in their typical convoluted form,<br />

and rapidly become flat and downy. No reverse pigmentation is present. No macroconidia<br />

and microconidia are seen in routine cultures, however numerous chlamydospores<br />

may be present in older cultures. However, characteristic antler “nail head”<br />

hyphae also known as “favic chandeliers” may be observed. A few distorted clavate<br />

microconidia may be formed by some isolates when grown on polished rice grains.<br />

RG-2 organism<br />

Key Features: clinical history, culture characteristics and microscopic morphology<br />

showing favic chandeliers.<br />

20 µm<br />

Culture and “favic chandeliers” of Trichophyton schoenleinii.<br />

Trichophyton schoenleinii is an anthropophilic fungus causing favus in humans. Favus<br />

is a chronic, scarring form of tinea capitis characterised by saucer-shaped crusted lesions<br />

or scutula and permanent hair loss. Invaded hairs remain intact and fluoresce<br />

a pale greenish yellow under Wood’s ultra-violet light. Favus was once common in<br />

Eurasia and North Africa, however its incidence is now in decline.


Descriptions of Medical Fungi 163<br />

Trichophyton soudanense Joyeux.<br />

Colonies (SDA) are slow-growing with a flat to folded, suede-like surface. Often there<br />

is a broad fringe of submerged growth. The surface mycelium and reverse pigment are<br />

characteristically a deep apricot-orange in colour. Microscopically, the hyphae often<br />

show reflexive or right-angle branching. Pyriform microconidia may occasionally be<br />

present and numerous chlamydospores are often found in older cultures. On BCPmilk<br />

solids agar, a thin halo of clearing usually appears in the milk solids around the<br />

colony edge at 7-10 days. RG-2 organism.<br />

T. soudanense appears to be genetically related to Trichophyton rubrum and T. violaceum<br />

(Graser et al. 2007), however we have maintained the current description until<br />

the taxonomy is clarified.<br />

Key Features: clinical history, culture characteristics and microscopic morphology<br />

showing reflexive hyphal branching and endothrix invasion of hair.<br />

20 µm<br />

Culture and “reflexive” hyphal branching in Trichophyton soudanense.<br />

Trichophyton soudanense is an anthropophilic fungus which is a frequent cause of<br />

tinea capitis in Africa. Invaded hairs show an endothrix infection but do not fluoresce<br />

under Wood’s ultra-violet light. Distribution is mainly in Africa with imported cases now<br />

reported from Europe, Brazil, Australia and USA.


164<br />

Descriptions of Medical Fungi<br />

Trichophyton terrestre Durie and Frey<br />

Teleomorphs: Arthroderma insingulare Padhye and Carmichael<br />

Arthroderma lenticulare Pore, Tsao and Plunkett<br />

Arthroderma quadrifidum Dawson and Gentles<br />

Colonies (SDA) are usually flat to downy with a suede-like to granular texture resembling<br />

T. mentagrophytes. The surface colour may range from white to cream, buff to<br />

yellow, or greenish-yellow. Reverse pigmentation is usually yellowish-brown although<br />

some variants have a deep rose-red reverse. Microconidia are large, clavate or pedicellate,<br />

usually exhibiting transition forms to more or less abundant lateral macroconidia.<br />

Macroconidia are clavate to cylindrical with rounded ends, smooth and thin-walled,<br />

and are two- to six-celled. Chlamydospores, hyphal spirals, racquet mycelium and<br />

antler hyphae may also be present. No growth at 37 O C. RG-1 organism.<br />

Trichophyton terrestre is a geophilic fungus of world-wide distribution which may occur<br />

as a saprophytic contaminant on humans and animals. It is not known to invade hair<br />

in vivo, but produces hair perforations in vitro.<br />

Key Features: culture characteristics and microscopic morphology.<br />

20 µm<br />

Culture and macroconidia of Trichophyton terrestre.


Descriptions of Medical Fungi 165<br />

Colonies (SDA) show considerable variation in texture and colour. They may be suedelike<br />

to powdery, flat with a raised centre or folded, often with radial grooves. The colour<br />

may vary from pale-buff to yellow, (the sulfureum form which resembles Epidermophyton<br />

floccosum), to dark-brown. The reverse colour varies from yellow-brown to reddish-brown<br />

to deep mahogany. Hyphae are relatively broad, irregular, much branched<br />

with numerous septa. Numerous characteristic microconidia varying in size and shape<br />

from long clavate to broad pyriform, are borne at right angles to the hyphae, which often<br />

remain unstained by lactophenol cotton blue. Very occasional smooth, thin-walled,<br />

irregular, clavate macroconidia may be present on some cultures. Numerous swollen<br />

giant forms of microconidia and chlamydospores are produced in older cultures. RG-2<br />

organism.<br />

Kaminski’s Dermatophyte Identification Scheme<br />

Littman Oxgall Agar: Restricted colony with cream, sometimes greyish, suede-like<br />

folded surface with no reverse pigment.<br />

Lactritmel Agar: Macroscopic and microscopic features as described above for the<br />

primary culture.<br />

Sabouraud’s Dextrose Agar with 5% NaCl: Very stunted slow growing colony with<br />

dark brown surface and reverse.<br />

1% Peptone Agar: Flat, white to cream suede-like surface with raised centre. No<br />

reverse pigment.<br />

Hydrolysis of Urea: positive at 5 days<br />

Trichophyton tonsurans Malmsten<br />

Nutritional Tests on Trichophyton Agars: results demonstrate a partial requirement<br />

for thiamine. T1 = vitamin free agar, T4 = vitamin free + thiamine agar.<br />

Hair Perforation Test: Positive within 14 days.<br />

T1 T4<br />

Key Features: microscopic morphology, culture characteristics, endothrix invasion of<br />

hairs and partial thiamine requirement.<br />

Trichophyton tonsurans is an anthropophilic fungus with a world wide distribution which<br />

causes inflammatory or chronic non-inflammatory finely scaling lesions of skin, nails<br />

and scalp. It is a common cause of tinea capitis in the Australian Aborigine and African<br />

Americans. Invaded hairs show an endothrix infection and do not fluoresce under<br />

Wood’s ultra-violet light.


166<br />

Descriptions of Medical Fungi<br />

Trichophyton tonsurans Malmsten<br />

20 µm<br />

Colonies, hyphae, microconidia and macroconidia of Trichophyton tonsurans.


Descriptions of Medical Fungi 167<br />

Teleomorph: Arthroderma benhamiae Ajello & Chang.<br />

Colonies (SDA) are slow growing, small, button or disc-shaped, white to cream-coloured,<br />

with a suede-like to velvety surface, a raised centre, and flat periphery with<br />

some submerged growth. Reverse pigment may vary from non-pigmented to yellow.<br />

Broad, irregular hyphae with many terminal and intercalary chlamydospores are<br />

present. Chlamydospores are often in chains. The tips of some hyphae are broad<br />

and club-shaped, and occasionally divided, giving the so-called “antler” effect. When<br />

grown on thiamine-enriched media, occasional strains produce clavate to pyriform microconidia<br />

borne singly along the hyphae. Macroconidia are only rarely produced, but<br />

when present have a characteristic tail or string-bean shape. RG-2 organism.<br />

Confirmatory Tests:<br />

Trichophyton verrucosum Bodin<br />

Growth at 37 O C: unlike other dermatophytes growth is enhanced at 37 O C<br />

Nutritional Requirements: all strains require thiamine and approximately 80% require<br />

thiamine and inositol. There is no growth on casein vitamin free agar (T1), minimal<br />

submerged growth on T1 + inositol (T2), good growth on T1 + inositol and thiamine<br />

(T3) and good growth on T1 + thiamine only (T4).<br />

All strains produce typical chains of chlamydospores, often referred to as “chains of<br />

pearls”, especially when grown on BCP milk solids glucose agar at 37 O C. Also when<br />

grown at 25 O C on milk solids glucose agar a halo of peripheral clearing of milk solids<br />

occurs within 7 days.<br />

Microscopic examination of young 4 to 5 day old colonies, grown from a very small<br />

inoculum, on Sabouraud’s’ dextrose agar containing 0.5% yeast extract and incubated<br />

at 30 O C, show characteristic terminal vesicles (not chlamydospores) at the tips of<br />

hyphae. The number of vesicles produced is greater from primary inoculations of skin<br />

scrapings or hairs.<br />

Key Features: culture characteristics and requirements for thiamine and inositol, large<br />

ectothrix invasion of hair, clinical lesions and history.<br />

Trichophyton verrucosum is a zoophilic fungus causing ringworm in cattle. Infections<br />

in humans result from direct contact with cattle or infected fomites and are usually<br />

highly inflammatory involving the scalp, beard or exposed areas of the body (ie. nails,<br />

skin). Invaded hairs show an ectothrix infection and fluorescence under Wood’s ultraviolet<br />

light has been noted in cattle but not in humans. Geographic distribution is<br />

world-wide.


168<br />

Descriptions of Medical Fungi<br />

Trichophyton verrucosum Bodin<br />

20 µm<br />

20 µm<br />

30 µm<br />

20 µm<br />

Trichophyton verrucosum showing clavate to pyriform microconidia,<br />

characteristic rat tail or string bean-shaped macroconidia, terminal vesicles<br />

at the tips of hyphae in young colonies and chains of chlamydospores.


Descriptions of Medical Fungi 169<br />

Trichophyton violaceum Sabouraud apud Bodin<br />

Colonies (SDA) are very slow growing, glabrous or waxy, heaped and folded and a<br />

deep violet in colour. Cultures often become pleomorphic, forming white sectors and<br />

occasional non-pigmented strains may occur. Hyphae are relatively broad, tortuous,<br />

much branched and distorted. Young hyphae usually stain well in lactophenol cotton<br />

blue, whereas older hyphae stain poorly and show small central fat globules and granules.<br />

No conidia are usually seen, although occasional pyriform microconidia have<br />

been observed on enriched media. Numerous chlamydospores are usually present,<br />

especially in older cultures. RG-2 organism.<br />

Nutritional Requirements: T. violaceum has a partial nutrient requirement for thiamine.<br />

There is minimal growth on casein vitamin-free agar (Trichophyton Agar No. 1),<br />

and slightly better growth on vitamin-free agar plus thiamine (Trichophyton Agar No.<br />

4). The partial requirement for thiamine separates this organism from T. gourvillii, T.<br />

rubrum, and other species that may produce purple pigmented colonies.<br />

Key Features: culture characteristics, partial thiamine requirement and endothrix hair<br />

invasion.<br />

Culture and chlamydospores of Trichophyton violaceum.<br />

20 µm<br />

Trichophyton violaceum is an anthropophilic fungus causing inflammatory or chronic<br />

non-inflammatory finely scaling lesions of skin, nails, beard and scalp, producing the<br />

so-called “black dot” tinea capitis. Distribution is world-wide, particularly in the Near<br />

East, Eastern Europe, USSR and North Africa. Invaded hairs show an endothrix<br />

infection and do not fluoresce under Wood’s ultra-violet light.


170<br />

Descriptions of Medical Fungi<br />

Trichosporon Behrend<br />

The genus Trichosporon is characterised by the development of hyaline, septate hyphae<br />

that fragment into oval or rectangular arthroconidia. Some blastoconidia are also<br />

seen. The colonies are usually raised and have a waxy appearance, which develop<br />

radial furrows and irregular folds.<br />

Following recent molecular studies, the genus has undergone major revision (Gueho<br />

et al. 1992, de Hoog et al. 2000, Rodriguez-Tudela et al. 2005) and 6 species of medical<br />

importance are described below. In particular, the name Trichosporon beigelii is<br />

now obsolete, and previously described infections reported in the literature under this<br />

name could in fact be due to any one of the species listed below.<br />

Trichosporon species are a minor component of normal skin flora, and are widely distributed<br />

in nature. They are regularly associated with the soft nodules of white piedra,<br />

and have been involved in a variety of opportunistic infections in the immunosuppressed<br />

patient. Disseminated infections are most frequently caused by T. asahii<br />

and have been associated with leukaemia, organ transplantation, multiple myeloma,<br />

aplastic anaemia, lymphoma, solid tumours and AIDS. Disseminated infections are<br />

often fulminate and widespread, with lesions occurring in the liver, spleen, lungs and<br />

gastrointestinal tract. Infections in non-immunosuppressed patients include endophthalmitis<br />

after surgical extraction of cataracts, endocarditis usually following insertion<br />

of prosthetic cardiac valves, peritonitis in patients on continuous ambulatory peritoneal<br />

dialysis (CAPD), and intravenous drug abuse.<br />

For descriptions of species, keys to taxa and additional information see Kurtzman<br />

and Fell (1988), Gueho et al. (1992), de Hoog et al. (2000), Rodriguez-Tudela et al.<br />

(2005).<br />

Key to medically important species (de Hoog et al. 2000).<br />

1. Growth with melibiose 2<br />

No growth with melibiose 3<br />

2. Tolerant to cycloheximide T. mucoides<br />

Not tolerant to cycloheximide T. cutaneum<br />

3. Growth with myo-inositol, no growth with L-arabinose T. inkin<br />

No growth with myo-inositol, growth with L-arabinose 4<br />

4. Colony with very slow growth; thallus consisting of clumps<br />

of meristematic cells (sarcinae) T. asteroides<br />

Colonies and microscopy otherwise 5<br />

5. Appressoria present in slide cultures T. ovoides<br />

Appressoria absent in slide cultures 6<br />

6. Arthroconidia barrel-shaped; thallus not meristematic T. asahii<br />

Arthroconidia elongate, or thallus meristematic T. asteroides


Descriptions of Medical Fungi 171<br />

Trichosporon asahii Akagi ex Sugita et al.<br />

Colonies (SDA) are white to cream-coloured, powdery, suede-like to farinose with radial<br />

furrows and irregular folds. Budding cells and lateral conidia are absent. Arthroconidia<br />

are barrel-shaped. Appressoria absent. This species assimilates L-arabinose<br />

but not melibiose. Growth at 37 O C. Most common species, especially from invasive<br />

infections. RG-2 organism.<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose - L-Rhamnose + D-Glucitol v<br />

Galactose + Raffinose - D-Glucosamine + α-M-D-glucoside +<br />

L-Sorbose v Melezitose v N-A-D-glucosamine + D-Gluconate +<br />

Sucrose v Soluble Starch v Glycerol v DL-Lactate v<br />

Maltose + D-Xylose v Erythritol + myo-Inositol v<br />

Cellobiose + L-Arabinose + Ribitol v Nitrate -<br />

Trehalose + D-Arabinose + Galactitol - 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol v D-Glucuronate +<br />

Culture, hyphae and arthroconidia of Trichosporon asahii.<br />

20 µm<br />

Antifungal<br />

MIC µg/mL<br />

Range MIC90 Antifungal<br />

MIC µg/mL<br />

Range MIC90 Fluconazole 0.25-16 8.0 Amphotericin B 0.25-16 8.0<br />

Itraconazole 0.03-16 0.5 Flucytosine 2-128 16<br />

Posaconazole 0.06-16 1.0 Caspofungin >8 >8<br />

Voriconazole 0.03-16 0.25 Anidulafungin >8 >8<br />

MIC data for T. asahii. Antifungal susceptibility may vary between species and<br />

resistant strains have been reported. Therefore, antifungal susceptibility testing of<br />

individual strains is recommended. Paphitou et al. (2002), Espinel-Ingroff (2003),<br />

Rodriguez-Tudela et al. (2005), Metin et al. (2005) and WCH in-house data.


172<br />

Descriptions of Medical Fungi<br />

Trichosporon asteroides (Rischin) Ota<br />

Colonies (SDA) are restricted, dry, cream-coloured, cerebriform, with radial furrows<br />

and irregular folds. The meristematic form is punctiform, brownish and consists of hyphae<br />

which swell and become multiseptate which may fall apart into smaller packets.<br />

Budding cells and lateral conidia are absent. Arthroconidia are elongate and hyphae<br />

are often present. Appressoria absent. This species assimilates L-arabinose but not<br />

myo-inositol. Growth at 37 O C is variable. Uncommon species usually associated with<br />

superficial infections. RG-2 organism.<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose - L-Rhamnose + D-Glucitol v<br />

Galactose + Raffinose - D-Glucosamine v α-M-D-glucoside +<br />

L-Sorbose v Melezitose + N-A-D-glucosamine + D-Gluconate +<br />

Sucrose + Soluble Starch + Glycerol + DL-Lactate +<br />

Maltose + D-Xylose + Erythritol + myo-Inositol -<br />

Cellobiose + L-Arabinose + Ribitol v Nitrate -<br />

Trehalose + D-Arabinose + Galactitol - 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol v D-Glucuronate +<br />

Trichosporon cutaneum (de Beurmann et al.) Ota<br />

Colonies (SDA) are cream-coloured, cerebriform, glabrous, with radial furrows and irregular<br />

folds. Budding cells abundant in primary cultures; hyphae developing in older<br />

cultures. Arthroconidia are cylindrical to ellipsoidal. Appressoria absent. This species<br />

assimilates melibiose; not tolerant to 0.1% cycloheximide. No growth at 37 O C. Uncommon<br />

species usually associated with superficial infections. RG-2 organism.<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose + L-Rhamnose + D-Glucitol +<br />

Galactose + Raffinose + D-Glucosamine v α-M-D-glucoside +<br />

L-Sorbose v Melezitose + N-A-D-glucosamine + D-Gluconate +<br />

Sucrose + Soluble Starch + Glycerol + DL-Lactate +<br />

Maltose + D-Xylose + Erythritol + myo-Inositol +<br />

Cellobiose + L-Arabinose + Ribitol + Nitrate -<br />

Trehalose + D-Arabinose v Galactitol - 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol + D-Glucuronate +<br />

Trichosporon inkin (Oho ex Ota) do Carmo-Sousa & van Uden<br />

Colonies (SDA) are restricted, white, finely cerebriform with a granular covering, without<br />

marginal zone, often cracking the media. Budding cells and lateral conidia absent.<br />

Arthroconidia are long cylindrical. Appressoria present in slide cultures. Sarcinae<br />

present on media with high sugar-content. This species assimilates myo-inositol but<br />

not melibiose. Growth at 37 O C. Usually associated with white piedra on pubic hairs.<br />

RG-2 organism.


Descriptions of Medical Fungi 173<br />

Trichosporon inkin (Oho ex Ota) do Carmo-Sousa & van Uden<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose - L-Rhamnose - D-Glucitol -<br />

Galactose v Raffinose - D-Glucosamine v α-M-D-glucoside +<br />

L-Sorbose v Melezitose + N-A-D-glucosamine + D-Gluconate +<br />

Sucrose + Soluble Starch + Glycerol v DL-Lactate +<br />

Maltose + D-Xylose + Erythritol + myo-Inositol +<br />

Cellobiose + L-Arabinose v Ribitol - Nitrate -<br />

Trehalose + D-Arabinose v Galactitol - 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol v D-Glucuronate +<br />

Trichosporon mucoides Gueho & M.Th. Smith<br />

Colonies (SDA) are moist and glabrous, white, cerebriform, heaped and folded. Budding<br />

cells present in primary cultures. Broadly clavate, terminal or lateral blastoconidia<br />

often present, becoming thick-walled with age. Arthroconidia are barrel-shaped. Appressoria<br />

absent. This species assimilates melibiose and is tolerant to 0.1% cycloheximide.<br />

Growth at 37 O C. Common species associated with superficial infections, white<br />

piedra and onychomycosis. RG-2 organism.<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose + L-Rhamnose + D-Glucitol +<br />

Galactose + Raffinose + D-Glucosamine + α-M-D-glucoside +<br />

L-Sorbose + Melezitose + N-A-D-glucosamine + D-Gluconate +<br />

Sucrose + Soluble Starch + Glycerol + DL-Lactate +<br />

Maltose + D-Xylose + Erythritol + myo-Inositol +<br />

Cellobiose + L-Arabinose + Ribitol + Nitrate -<br />

Trehalose + D-Arabinose + Galactitol + 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol + D-Glucuronate +<br />

Trichosporon ovoides Behrend<br />

Colonies (SDA) are restricted, white, granular, folded at the centre, with a flat marginal<br />

zone. Budding cells and lateral conidia absent. Arthroconidia are cylindrical. Appressoria<br />

present in slide cultures. This species does not assimilate melibiose, but tolerates<br />

0.1% cycloheximide. Growth at 37 O C is variable. Uncommon species usually<br />

associated with superficial infections, like white piedra. RG-2 organism.<br />

Assimilation Tests: + Positive, - Negative, v Variable, w Weak, s Slow<br />

Glucose + Melibiose - L-Rhamnose + D-Glucitol v<br />

Galactose + Raffinose v D-Glucosamine v α-M-D-glucoside +<br />

L-Sorbose v Melezitose v N-A-D-glucosamine + D-Gluconate +<br />

Sucrose + Soluble Starch + Glycerol v DL-Lactate +<br />

Maltose + D-Xylose + Erythritol + myo-Inositol +<br />

Cellobiose + L-Arabinose v Ribitol - Nitrate -<br />

Trehalose v D-Arabinose v Galactitol - 2-K-D-gluconate +<br />

Lactose + D-Ribose + D-Mannitol + D-Glucuronate +


174<br />

Descriptions of Medical Fungi<br />

Trichothecium roseum (Persoon) Link ex Gray<br />

Colonies are moderately fast growing, flat, suede-like to powdery, initially white but<br />

becoming rosy, pink or orange with age. The conidiophores are indistinguishable<br />

from the vegetative hyphae until the first conidium is produced. They are erect, unbranched,<br />

often septate near the base, more or less rough-walled, bearing basipetal<br />

zig-zag (alternating) chains of conidia at the apex. Note: the conidiophore is progressively<br />

shortened with the formation of each conidium i.e. retrogressive conidial development.<br />

Conidia are two-celled ellipsoidal to pyriform, with an obliquely truncate basal<br />

scar, hyaline, smooth to delicately roughened and thick-walled.<br />

Trichothecium roseum has a world-wide distribution and is often isolated from decaying<br />

plant substrates, soil, seeds of corn, and food-stuffs (especially flour products). It<br />

is occasionally isolated as a saprophyte in the clinical laboratory. RG-1 organism.<br />

Trichothecium roseum should not be confused with Microsporum nanum. Colonies of<br />

the latter may be pinkish-buff in colour and also produce ovoid to pear-shaped, mostly<br />

two-celled macroconidia with thin, verrucose walls. However, M. nanum usually produces<br />

a red-brown reverse pigment and the two-celled macroconidia are sessile and<br />

formed singly, sometimes on stalks, on undifferentiated conidiophores which do not<br />

undergo further change or produce secondary conidia. Note: conidia are not produced<br />

in basipetal chains as in T. roseum. Finally, M. nanum will perforate hair in vitro.<br />

Key Features: hyphomycete, basipetal zig-zag chains of two-celled conidia showing<br />

retrogressive development where the conidiophore becomes progressively shorter.<br />

For descriptions of species, keys to taxa and additional information see McGinnis<br />

(1980), Domsch et al. (1980), Rippon (1988) and Samson et al. (1995).<br />

20 µm<br />

Conidiophores of T. roseum demonstrating retrogressive conidial development.


Descriptions of Medical Fungi 175<br />

Ulocladium Preuss<br />

Colonies are rapid growing, brown to olivaceous-black or greyish and suede-like to<br />

floccose. Microscopically, numerous, usually solitary, multi-celled conidia (dictyoconidia)<br />

are formed through a pore (poroconidia) by a sympodially elongating geniculate<br />

conidiophore. Conidia are typically obovoid (narrowest at the base), dark brown and<br />

often rough-walled. Seven species have been described, all being saprophytes. RG-<br />

1 organism.<br />

Species of Ulocladium should not be confused with other poroconidial genera such as<br />

Stemphylium, Alternaria, Bipolaris, Exserohilum, Dreschlera and Curvularia.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1970 and<br />

1976), Domsch et al. (1980), Rippon (1988), Samson et al. (1995) and de Hoog et al.<br />

(2000).<br />

Antifungal<br />

Conidia of Ulocladium.<br />

10 µm<br />

MIC µg/mL<br />

MIC µg/mL<br />

Antifungal<br />

Range Range<br />

Fluconazole 8->64 Amphotericin B 1->16<br />

Itraconazole 0.06->16 Flucytosine >128<br />

Voriconazole 0.25<br />

Very limited data. Antifungal susceptibility testing of individual strains is<br />

recommended. Pujol et al. (2000) and WCH in-house data.


176<br />

Descriptions of Medical Fungi<br />

Veronaea botryosa Ciferri & Montemartini<br />

Colonies grow rapidly and are suede-like to downy, greyish-brown to blackish-brown.<br />

Conidiophores are erect, straight or flexuose, occasionally branched and are usually<br />

geniculate, due to the sympodial development of the conidia. They are smooth-walled,<br />

pale to medium olivaceous-brown, up to 250 µm long and 2-4 µm wide. Conidia are<br />

pale brown, two-celled, cylindrical with a truncated base, smooth-walled or slightly verrucose,<br />

5-12 x 3-4 µm. RG-1 organism.<br />

This genus is very similar to Rhinocladiella, however the conidia are typically twocelled.<br />

Occasional skin infections have been reported from humans.<br />

For descriptions of species, keys to taxa and additional information see Ellis (1971)<br />

and de Hoog et al. (2000).<br />

Conidiophores and conidia of Veronaea botryosa.<br />

10 µm


Descriptions of Medical Fungi 177<br />

Verticillium Nees ex Link<br />

Colonies are fast growing, suede-like to downy, white to pale yellow in colour, becoming<br />

pinkish brown, red, green or yellow with a colourless, yellow or reddish brown reverse.<br />

Conidiophores are usually well differentiated and erect, verticillately branched<br />

over most of their length, bearing whorls of slender awl-shaped divergent phialides.<br />

Conidia are hyaline or brightly coloured, mostly one-celled, and are usually borne in<br />

slimy heads (glioconidia).<br />

Members of this genus are often isolated from the environment. It has been reported<br />

as a rare agent of mycotic keratitis. RG-1 organism.<br />

Key Features: hyphomycete, verticillate branched conidiophores bearing whorls of<br />

awl-shaped, divergent phialides.<br />

For descriptions of species, keys to taxa and additional information see Domsch et al.<br />

(1980), McGinnis (1980), Rippon (1988), Samson et al. (1995), de Hoog et al. (2000).<br />

20 µm<br />

Conidiophores, phialides and conidia of Verticillium.


178<br />

Descriptions of Medical Fungi<br />

Calcofluor White with 10% KOH.<br />

For the direct microscopic examination of skin scrapings, hairs, nails and other clinical<br />

specimens for fungal elements. This as a very sensitive method, however, a fluorescence<br />

microscope with the correct ultraviolet filters is required (Hageage and Harrington,<br />

1984; Hollander et al., 1984; Monheit et al., 1984).<br />

Solution A: Potassium hydroxide reagent.<br />

Potassium hydroxide 10 g<br />

Glycerine 10 mL<br />

Distilled water 80 mL<br />

Solution B: Calcofluor white reagent.<br />

Calcofluor white 0.5 g<br />

Evans blue 0.02 g<br />

Distilled water 50 mL<br />

Mix one drop of each solution on the centre of a clean microscope slide.<br />

Place the specimen in the solution and cover with a coverslip.<br />

Potassium Hydroxide (KOH) with Chlorazol Black.<br />

For the direct microscopic examination of skin scrapings, hairs, nails and other clinical<br />

specimens for fungal elements. Note: Parker Quink ink is no longer available.<br />

Potassium hydroxide 10 g<br />

Coral Azole E Black (0.1% - 100mg in 100ml) 10 mL<br />

Glycerol 10 mL<br />

Distilled water 80 mL<br />

Using sterile technique, remove a small portion of the specimen with an<br />

inoculation needle and mount in a drop of KOH on a clean microscope<br />

slide. Cover with a coverslip, squash the preparation with the butt of the<br />

inoculation needle and then blot off the excess fluid.<br />

Indian Ink Mounts.<br />

MICROSCOPY STAINS & TECHNIQUES<br />

For the direct microscopic examination of CSF for Cryptococcus species. Place a drop<br />

of Indian Ink on the specimen, mix well with a sterilised loop, and cover with a coverslip.<br />

Best brands to use are “Pelikan” or “Talons” Indian Ink.


Descriptions of Medical Fungi 179<br />

Lactophenol Cotton Blue (LPCB).<br />

For the staining and microscopic identification of fungi.<br />

Cotton Blue (Aniline Blue) 0.05 g<br />

Phenol Crystals (C 6 H 5 O 4 ) 20 g<br />

Glycerol 40 mL<br />

Lactic acid (CH 3 CHOH COOH) 20 mL<br />

Distilled water 20 mL<br />

This stain is prepared over two days.<br />

1. On the first day, dissolve the Cotton Blue in the distilled water. Leave<br />

overnight to eliminate insoluble dye.<br />

2. On the second day, wearing gloves add the phenol crystals to the lactic<br />

acid in a glass beaker. Place on magnetic stirrer until the phenol is<br />

dissolved.<br />

3. Add the glycerol.<br />

4. Filter the Cotton Blue and distilled water solution into the phenol/glycerol/<br />

lactic acid solution. Mix and store at room temperature.<br />

Direct Microscopic Mounts or Squash Preparations.<br />

Using sterile technique, remove a small portion of the colony with an inoculation needle<br />

and mount in a drop of Lactophenol Cotton Blue on a clean microscope slide.<br />

Cover with a coverslip, squash the preparation with the butt of the inoculation needle<br />

and then blot off the excess fluid.<br />

Cellotape Flag Preparations.<br />

MICROSCOPY STAINS & TECHNIQUES<br />

An excellent technique for the rapid mounting of sporulating fungi because it keeps<br />

more of the reproductive structures intact.<br />

1. Using clear 2cm wide cellotape and a wooden applicator stick (orange<br />

stick) make a small cellotape flag (2 x 2 cm).<br />

2. Using sterile technique, gently press the sticky side of the flag onto the<br />

surface of the culture.<br />

3. Remove and apply a drop of 95% alcohol to the flag, this acts as a wetting<br />

agent and also dissolves the adhesive glue holding the flag to the<br />

applicator stick.<br />

4. Place the flag onto a small drop of Lactophenol cotton blue on a clean<br />

glass slide, remove the applicator stick and discard, add another drop<br />

of stain, cover with a coverslip, gently press and mop up any excess<br />

stain.


180<br />

Descriptions of Medical Fungi<br />

Slide Culture Preparations.<br />

MICROSCOPY STAINS & TECHNIQUES<br />

In order to accurately identify many fungi it is essential to observe the precise arrangement<br />

of the conidiophores and the way in which spores are produced (conidial ontogeny).<br />

Riddel’s simple method of slide culturing (Mycologia 42:265, 1950) permits fungi<br />

to be studied virtually in situ with as little disturbance as possible. A simple modification<br />

of this method using a single agar plate is described below.<br />

One plate of nutrient agar; potato dextrose is recommended, however,<br />

some fastidious fungi may require harsher media to induce sporulation like<br />

Cornmeal agar or Czapek Dox agar.<br />

1. Using a sterile blade cut out an agar block (7 x 7 mm) small enough to<br />

fit under a coverslip.<br />

2. Flip the block up onto the surface of the agar plate.<br />

3. Inoculate the four sides of the agar block with spores or mycelial<br />

fragments of the fungus to be grown.<br />

4. Place a flamed coverslip centrally upon the agar block.<br />

5. Incubate the plate at 26 O C until growth and sporulation have<br />

occurred.<br />

6. Remove the cover slip from the agar block.<br />

7. Apply a drop of 95% alcohol as a wetting agent.<br />

8. Gently lower the coverslip onto a small drop of Lactophenol cotton blue<br />

on a clean glass slide.<br />

9. The slide can be left overnight to dry and later sealed with fingernail<br />

polish.<br />

10. When sealing with nail polish use a coat of clear polish followed by one<br />

coat of red-coloured polish.<br />

Simple agar block method, inoculated on four sides with cover slip<br />

on top. Make at least 2 slides per culture.


Descriptions of Medical Fungi 181<br />

Bird Seed Agar (Staib, 1987).<br />

for selective isolation of Cryptococcus neoformans and C. gattii.<br />

Guizotia abyssinica (niger seed) 50 g Glucose 1 g<br />

KH PO (potassium dihydrogen 1 g Creatinine 1 g<br />

2 4<br />

orthophosphate)<br />

Bacto Agar (BD 214010) 15 g Distilled water 1000 mL<br />

Penicillin G (20 units/mL) 1 mL Gentamicin (40 mg/mL) 1 mL<br />

1. Grind seeds of Guizotia abyssinica as finely as possible with an electric mixer<br />

and add to 1000 mL distilled water in a stainless steel jug.<br />

2. Boil for 30 minutes, pass through filter paper and adjust volume to 1000 mL.<br />

3. Add remaining ingredients except Bacto Agar to filtrate and dissolve.<br />

If required: Cool to room temperature and adjust pH to 5.5.<br />

Dispense into 500 mL bottles.<br />

4. Add 7.5 g Bacto Agar to each 500 mL reagent bottle.<br />

5. Autoclave 110OC for 20 minutes.<br />

6. Cool to 48OC and add 0.5 mL Penicillin G and 0.5 mL Gentamicin to each 500<br />

mL of Bird Seed Agar.<br />

7. Mix gently and pour into 90 mm plastic petri dishes.<br />

Bromcresol Purple Milk Solids Glucose Agar (BCP-MS-G).<br />

for the differentiation of Trichophyton species (Kane et al. 1977).<br />

Solution A:<br />

Distilled water 1000 mL<br />

Skim milk powder (Carnation Brand) 80 g<br />

Bromcresol (or bromocresol) purple<br />

2 mL<br />

(1.6% solution in alcohol)<br />

Dissolve in 2 litre flask and autoclave 10 psi/15 minutes.<br />

Solution B:<br />

Glucose 40 g Distilled water 200 mL<br />

Dissolve and autoclave at 10 psi/8minutes.<br />

Solution C:<br />

SPECIALISED CULTURE MEDIA<br />

Bacto Agar (BD 214010) 30 g Distilled water 800 mL<br />

Soak for 15 minutes in 3 litre flask; autoclave at 15 psi/15 minutes<br />

To make media; add solution A and B to solution C. Adjust final pH to 6.6.<br />

Aseptically dispense for slopes (7 mL amounts into 30 mL disposable bottles).<br />

Caution: Do not substitute casein for skim milk. Check pH is 6.6.


182<br />

Descriptions of Medical Fungi<br />

CDBT (Creatinine dextrose bromothymol blue thymine agar).<br />

for differentiation of Cryptococcus neoformans var. neoformans and<br />

Cryptococcus neoformans var. grubii (Irokanulo et al. 1994).<br />

Solution A:<br />

Creatinine 1 g Dextrose 0.5 g<br />

KH 2 PO 4 1 g MgSO 4 7H 2 O 0.5 g<br />

Thymine 0.1 g Distilled water 980 mL<br />

1. Dissolve ingredients in small beaker and adjust pH to 5.6<br />

2. Store in refrigerator.<br />

Solution B (Aqueous Bromothymol Blue):<br />

Bromothymol blue 0.4 g 0.01N NaOH 64 mL<br />

Distilled water 36 mL<br />

1. Dissolve the Bromothymol Blue in the NaOH<br />

2. Add to the water.<br />

To prepare medium (1 litre for plates):<br />

Solution A 980 mL Solution B 20 mL<br />

Bacto Agar (BD 214010) 20 g<br />

Autoclave to 121 O C for 15 minutes, cool to 48 O C and pour plates.<br />

CGB (L-Canavanine glycine bromothymol blue agar).<br />

for differentiation of Cryptococcus neoformans and Cryptococcus gattii<br />

(Kwon-Chung et al. 1982).<br />

Solution A:<br />

Glycine Univar 10 g KH 2 PO 4 1 g<br />

MgSO 4 1 g Thiamine HCl 1 mg<br />

L-canavanine sulphate 30 mg Distilled water 100 mL<br />

1. Dissolve ingredients in small beaker and adjust pH to 5.6<br />

2. Filter sterilise solution using 0.22 µm filter.<br />

3. Store in refrigerator.<br />

Solution B (Aqueous Bromothymol Blue):<br />

Bromothymol blue 0.4 g 0.01N NaOH 64 mL<br />

Distilled water 36 mL<br />

1. Dissolve the Bromothymol Blue in the NaOH<br />

2. Add to the water.<br />

To prepare medium (1 litre for plates):<br />

SPECIALISED CULTURE MEDIA<br />

Distilled water 980 mL Solution B 20 mL<br />

Bacto Agar (BD 214010) 20 g<br />

1. Autoclave to 121 O C for 15 minutes, cool to 48 O C.<br />

2. For plates add 100 mL of the filtered solution A and mix. Dispense in<br />

plates.


Descriptions of Medical Fungi 183<br />

SPECIALISED CULTURE MEDIA<br />

Cornmeal Agar.<br />

for routine cultivation and identification of fungi.<br />

Cornmeal agar (Oxoid CM 0103) 8.5 g<br />

Distilled water 500 mL<br />

1. Mix dry ingredients into 100 mL H 2 O, boil remaining water.<br />

2. Add boiling water to mixture and bring to boil.<br />

3. Autoclave for 10 minutes at 120 O C, then slope on racks.<br />

Cornmeal Glucose Sucrose Yeast Extract Agar.<br />

for zygomycete sporulation<br />

Cornmeal agar (Oxoid CM 0103) 17 g<br />

Dextrose (Glucose) 2 g<br />

Sucrose 3 g<br />

Yeast extract 1 g<br />

Distilled water 1000 mL<br />

1. Mix dry ingredients into 100 mL H 2 O, boil remaining water.<br />

2. Add boiling water to mixture and bring to boil.<br />

3. Dispense for slopes.<br />

4. Autoclave for 10 minutes at 120 O C, remove and slope.<br />

Czapek Dox Agar.<br />

for routine cultivation of fungi, especially Aspergillus, Penicillium,<br />

and non-sporulating moulds.<br />

Czapek Dox Agar (Oxoid CM97) 45.4 g<br />

Distilled water 1000 mL<br />

1. Soak the ingredients in small amount of water.<br />

2. Bring remaining water to boil, add to soaking ingredients and bring to<br />

the boil again, stirring continuously.<br />

3. Dispense for slopes as required.<br />

4. Autoclave at 121 O C for 10 minutes, remove and slope or pour for plates<br />

as required.<br />

Dixon’s Agar (modified).<br />

for primary isolation and cultivation of Malassezia species.<br />

Malt extract (Oxoid L39) 9 g Bacto Tryptone 1.5 g<br />

Ox-bile Desiccated (Oxoid L50) 5 g Tween 40 2.5 mL<br />

Oleic acid 0.5 g Glycerol 0.5 mL<br />

Bacto Agar 3 g Distilled water 250 mL<br />

1. Soak ingredients in a little of the water.<br />

2. Bring remaining water to boil, add to the soaking ingredients and bring<br />

to the boil again constantly stirring.<br />

3. Dispense for slopes (7 mL amounts into 30 mL disposable bottles.<br />

4. Autoclave at 121 O C for 10 minutes and then slope.


184<br />

Descriptions of Medical Fungi<br />

SPECIALISED CULTURE MEDIA<br />

Hair Perforation Test.<br />

for the differentiation of Trichophyton species.<br />

Blonde pre-pubital hair cut into short pieces (1 cm) 10-20 hairs<br />

Distilled water 5 mL<br />

1. Autoclave hair at 121 O C for 10 minutes and store in sterile container.<br />

2. Place 10-20 short pieces of hair in 5 mL water in vial.<br />

3. Inoculate with small fragments of the test fungus.<br />

4. Incubate at room temperature.<br />

5. Individual hairs are removed at intervals up to 4 weeks and examined<br />

microscopically in lactophenol cotton blue. Isolates of T. mentagrophytes<br />

produce marked localised areas of pitting and marked erosion whereas<br />

those of T. rubrum do not.<br />

Lactritmel Agar.<br />

for the production of pigment by Trichophyton species.<br />

Skimmed milk powder<br />

7 g<br />

(use only Dutch Jug skimmed milk powder)<br />

Honey 10 g<br />

Cornmeal agar (Oxoid CM 0103) 17 g<br />

Chloramphenicol 1 x 250 capsule<br />

Distilled water 1000 mL<br />

1. Weigh skimmed milk into stainless steel jug. Slowly add some water,<br />

mixing milk into smooth paste. Continue adding small quantities of<br />

water until powder is dissolved (about 150 mL).<br />

2. Weigh other ingredients into skimmed milk and allow to soak.<br />

3. Boil remaining water, and with it wash out honey from beaker.<br />

4. Add to other ingredients and boil.<br />

5. Dispense for slopes (7 mL).<br />

6. Autoclave for 10 minutes at 115OC. 7. On removal from autoclave allow to stand 5 minutes then shake and<br />

slope on racks.<br />

Note: Do not filter or adjust pH in any way<br />

Littman Oxgall Agar.<br />

for the differentiation of Trichophyton species.<br />

Littman Oxgall Agar (US Biological L3025) 27.5 g<br />

Distilled water 500 mL<br />

1. Soak agar in 100 mL of water in stainless steel jug. Boil remaining<br />

400mL in a separate jug.<br />

2. When water has boiled add to soaking agar and reboil, stirring<br />

constantly.<br />

3. Dispense for slopes.<br />

4. Autoclave for 10 minutes at 121 O C, remove and slope.


Descriptions of Medical Fungi 185<br />

SPECIALISED CULTURE MEDIA<br />

Malt Extract Agar.<br />

for routine cultivation and identification of fungi.<br />

Oxoid Malt Extract (L39) 20 g<br />

Bacto Agar (BD 214010) 20 g<br />

Distilled water 1000 mL<br />

1. Dissolve malt extract in a plastic beaker and pH the solution to pH 6.5<br />

with NaOH.<br />

2. Soak agar in small quantity of solution. Bring remaining solution to<br />

the boil, stirring constantly.<br />

3. Add to soaking agar. Bring to boil, stirring constantly.<br />

4. Dispense for slopes as required.<br />

5. Autoclave at 121 O C for 10 minutes, remove and slope or pour for<br />

plates as required.<br />

1% Peptone Agar.<br />

for the differentiation of Trichophyton species.<br />

Tryptone Peptone (BD 211705) 5 g<br />

Bacto Agar (BD 214010) 10 g<br />

Distilled water 500 mL<br />

1. Soak agar and peptone in about 50 mL of water.<br />

2. Boil remaining water, add this to soaking ingredients and bring to boil<br />

again.<br />

3. Dispense for slopes (7 mL).<br />

4. Autoclave for 10 minutes at 121 O C, then slope on racks.<br />

Potato Dextrose Agar.<br />

for routine cultivation and identification of fungi.<br />

Potato Dextrose Agar (Oxoid CM139) 39 g<br />

Distilled water 1000 mL<br />

1. Soak potato dextrose agar in small amount of the water in a stainless<br />

steel jug.<br />

2. Boil remaining water, add to soaking ingredients, bring to the boil,<br />

stirring constantly.<br />

3. Dispense for slopes as required.<br />

4. Autoclave at 121 O C for 15 minutes. Remove and slope or pour for<br />

plates as required.<br />

Rice Grain Slopes.<br />

to induce sporulation and for differentiation of M. audouinii and M. canis.<br />

Polished rice grains Distilled water<br />

1. Place ~ 1/2 teaspoon rice grains into wide neck 20 mL glass vials.<br />

2. Add 8 mL distilled water to each vial.<br />

3. Lid, then slope on racks ensuring rice grains are evenly distributed.<br />

4. Autoclave racks at 121 O C for 15 minutes.


186<br />

Descriptions of Medical Fungi<br />

SPECIALISED CULTURE MEDIA<br />

Sabouraud Dextrose Agar with Cycloheximide, Chloramphenicol,<br />

Gentamicin and Yeast Extract.<br />

for the primary isolation and cultivation of dermatophytes.<br />

Sabouraud Dextrose Agar (Oxoid CM41) 65 g<br />

Cycloheximide (Actidione) 0.5 g<br />

Chloramphenicol 1 x 250 capsule<br />

Gentamicin (40mg/mL) 0.56 mL<br />

Yeast extract 5 g<br />

Distilled water 1000 mL<br />

1. Soak all ingredients, except Gentamicin, in 100 mL water.<br />

2. Boil remaining water, add to soaking ingredients, and bring to boil to<br />

dissolve, stirring well to prevent from charring.<br />

3. Add the Gentamicin. Mix well.<br />

4. Dispense for slopes as required.<br />

5. Autoclave at 121 O C for 10 minutes. Remove and slope, or pour for plates<br />

as required.<br />

Sabouraud Dextrose Agar with Chloramphenicol and Gentamicin.<br />

for primary isolation and routine culture of yeasts and moulds.<br />

Sabouraud Dextrose Agar (Oxoid CM41) 65 g<br />

Chloramphenicol 1 x 250 capsule<br />

Gentamicin (40mg/mL) 0.56 mL<br />

Distilled water 1000 mL<br />

See above method for Sabouraud Dextrose Agar with Cycloheximide,<br />

Chloramphenicol, Gentamicin and Yeast Extract.<br />

Sabouraud Dextrose Agar with 5% Salt.<br />

for the differentiation of Trichophyton species.<br />

Sabouraud Dextrose Agar (Oxoid CM41) 32.5 g<br />

Sodium Chloride NaCl (Univar 465) 25 g<br />

Distilled water 500 mL<br />

1. Soak ingredients in approximately 100 mL water.<br />

2. Bring remaining water to boil, add to soaking ingredients.<br />

3. Dispense for slopes (7 mL).<br />

4. Autoclave at 118 O C for 10 minutes, then slope on racks.


Descriptions of Medical Fungi 187<br />

Tap Water Agar.<br />

for the stimulation of sporulation in Apophysomyces and Saksenaea isolates.<br />

Bacto Agar (BD 214010) 15 g<br />

Distilled water 1000 mL<br />

1. Add agar to water in stainless steel jug, allow to soak.<br />

2. Dispense for slopes.<br />

3. Autoclave at 118 O C for 10 minutes, remove and slope.<br />

Urease Agar Slopes with 0.5% Glucose.<br />

for the differentiation of Urease producing organisms.<br />

Urease glucose broth base:<br />

Urea, broth base (Oxoid CM71) 0.9 g<br />

Glucose 5 g<br />

Distilled water 450 mL<br />

1. Add the Urea broth base and glucose to the distilled water in a 500mL<br />

beaker.<br />

2. Dispense in 5 X 90 mL amounts.<br />

3. Autoclave at 115 O C for 20 mins.<br />

4. When cool, label and store in the fridge.<br />

Method to make slopes:<br />

SPECIALISED CULTURE MEDIA<br />

40% Urea Solution (Oxoid SR 20) 10 mL<br />

Bacto Agar (BD 214010) 3 g<br />

Distilled water 100 mL<br />

1. Add 3.0 grams of agar to 100 mL of distilled water in a 250 mL pyrex<br />

bottle.<br />

2. Autoclave at 121 O C for 15 minutes and place in 50 O C water bath.<br />

3. When cool add 90 mL of the Urease broth with glucose and the 10 mL<br />

of 40% urea solution to agar and dispense in 3 mL aliquots and slope<br />

on racks.<br />

Vitamin Free Agar (Trichophyton Agar No.1).<br />

for the differentiation of Trichophyton species.<br />

Trichophyton Agar No. 1 (BD 287710) 11.8 g<br />

Distilled water 200 mL<br />

1. Add agar to water in stainless steel jug, allow to soak.<br />

2. Bring to boil to dissolve, stirring constantly.<br />

3. Once boiled remove immediately to avoid discolouration.<br />

4. Dispense for slopes.<br />

5. Autoclave at 118 O C for 10 minutes, remove and slope.


188<br />

Descriptions of Medical Fungi<br />

REFERENCES<br />

Adam, R.D., M.L. Paquin, E.A. Petersen et al. (1986). Phaeohyphomycosis caused<br />

by the fungal genera Bipolaris and Exserohilum. A report of 9 cases and review of<br />

the literature. Medicine. 65:203-217.<br />

Ajello, L. 1957. Coccidioides immitis: Isolation procedures and diagnostic criteria.<br />

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