a dichotomous key approach

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1 a dichotomous key approach
Fungi Identification a dichotomous key approach

2 Microscopic appearance of colonies:
budding cells few or no hyphae hyphae seen

3 Macroscopic appearance of colonies:
colonies black colonies white cream pink red Aureobasidium Chapter 8 Yeast

4 Hyphal appearance: septate aseptate Mucoraceous moulds

5 (arthroconidia absent)
Conidial appearance: arthroconidia (other forms absent) Other forms (arthroconidia absent) Chapter 3

6 Conidia formed in chains:
present absent

7 Conidial chains in branches:
present absent CHAPTER 6 CHAPTER 7

8 Conidial chain arrangement:
Positive for dermatophyte chains formed singly on sides of hyphae or on short branches Negative for dermatophyte chains formed in succession at the same point, aggregating in masses fruiting bodies present? CHAPTER 4, 5, 6 CHAPTER 8 CHAPTER 10

9 Neoscytalidium dimidiatum
ARTHROSPORIC MOULDS Colony appearance: colony dark brown or black colony white or cream Neoscytalidium dimidiatum

10 Arthrospore arrangement:
ARTHROSPORIC MOULDS Arthrospore arrangement: Arthrospores regularly alternating with empty cells Arthrospores not separated by empty cells

11 ARTHROSPORIC MOULDS Arthrospore Size: Wider than 2 microns
Mostly microns wide Coccidioides spp Malbranchea spp.

12 Colony with little aerial mycelium
ARTHROSPORIC MOULDS Colony morphology Colony with little aerial mycelium Colony floccose Geotrichum spp OR Trichosporon spp

13 ARTHROSPORIC MOULDS Culture growth speed:
Rapid growth (diameter >20mm in 1 week) Slow growth Onychocola canadensis

14 ARTHROSPORIC MOULDS Arthrospore numbers:
abundant, 4-8 microns wide, rounded appearance few, 2-5 microns wide, flat-ended Hyaline variant of Neoscytalidium dimidiatum Basidiomycete moulds

15 Presence of blastoconidia:
ARTHROSPORIC MOULDS Presence of blastoconidia: Present Absent Trichosporon spp Geotrichum spp

16 DERMATOPHYTIC MOULDS Pattern of conidia: Macroconidia predominant
Microconidia predominant Neither macro nor micro conidia present

17 Surface of macroconidia:
DERMATOPHYTIC MOULDS Surface of macroconidia: Rough Smooth

18 Presence of terminal beak on macroconidia
DERMATOPHYTIC MOULDS Presence of terminal beak on macroconidia Present Absent Microsporum gypseum Microsporum fulvum

19 DERMATOPHYTIC MOULDS Size of Macroconidia Large >50 microns Smaller
Microsporum canis Microsporum equinum

20 DERMATOPHYTIC MOULDS Colony colour: Khaki-brown to greenish-yellow
White, cream or yellow Some purple coloration Trichophyton terrestre Trichophyton ajelloi Trichophyton rubrum (granular form) Epidermophyton floccosum

21 DERMATOPHYTIC MOULDS Colony morphology Colony: OTHERWISE
floccose/velvety, white with red-brown reverse, peg-like microconidia velvety/granular, cream with dark brown reverse, round microconidia Colony: OTHERWISE Trichophyton rubrum

22 DERMATOPHYTIC MOULDS Microconidia number:
Spiral hyphae, microconidia rare (foot isolate) brown veins on colony reverse, spiral hyphae, microconidia common Trichophyton interdigitale Trichophyton mentagrophytes

23 DERMATOPHYTIC MOULDS Microconidia shape
small and peg-like small, oval-round with a wide base larger, oval (colony with brown reverse)

24 DERMATOPHYTIC MOULDS Colony Morphology: flat, white, velvety,
bright yellow reverse buff-cream, velvety, brown reverse with yellow edge floccose, white, reverse NOT yellow Trichophyton erinacei Trichophyton equinum

25 DERMATOPHYTIC MOULDS Colony Growth Rate: Slow-growing Intermediate
(<10 mm/wk) Intermediate (10-15mm/wk) Rapid (20-30mm/wk) Trichophyton verrucosum (sporulating variants) Trichophyton rubrum (poorly-pigmented variants) Trichophyton interdigitale (downy form)

26 DERMATOPHYTIC MOULDS Colony Morphology
heaped, pink or yellow tinge, reverse yellow, reflexive branching at colony edge (slow) reverse brownish, broad-based microconidia, formed at end of hyphal side branches Trichophyton soudanense Microsporum persicolor

27 DERMATOPHYTIC MOULDS Colony Morphology
granular/velvety, reddish colour, reverse dark-brown, clear white edge granular/velvety, brown to cream, reverse dark-brown with colourless edge Trichophyton rubrum (granular form) Microsporum tonsurans

28 DERMATOPHYTIC MOULDS Growth Rate: Moderately Rapid (>15mm/wk)
Slow (<15mm/wk)

29 Loosely floccose or velvet
DERMATOPHYTIC MOULDS Colony Morphology: Densely floccose Loosely floccose or velvet Trichophyton rubrum

30 DERMATOPHYTIC MOULDS Colony Colour:
Reverse pale pinkish-brown, pectinate hyphae seen Reverse yellow Microsporum audouinii

31 DERMATOPHYTIC MOULDS Colony Colour:
Reverse intense orange-yellow, mostly no aerial hyphae Reverse clear-yellow, mostly floccose Trichophyton interdigitale (nodular form) Microsporum canis

32 DERMATOPHYTIC MOULDS Colony Colour: dark purple-brown,
little or no aerial growth white, grey or cream, floccose or folded Trichophyton violaceum

33 DERMATOPHYTIC MOULDS Colony Morphology:
colony strongly folded colony almost microscopic, floccose Trichophyton verrucosum

34 Microscopic appearance:
DERMATOPHYTIC MOULDS Microscopic appearance: Nail-head hyphae and favic chandeliers present, grows without thiamine Nail-head hyphae and favic chandeliers absent, thiamine dependent Trichophyton schoenleinii Trichophyton concentricum

35 Paracoccidioides brasiliensis
Order onygenales Presence of conidia: absent present Paracoccidioides brasiliensis

36 Order onygenales Conidia morphology:
conidia large, spherical, rough-walled or tuberculate Not as described Histoplasma capsulatum

37 Order onygenales Conidia size: small <4 microns long longer than

38 Order onygenales Conidia arrangement:
broad-based on acutely angled conidiophores very narrow based, on sides of hyphae or on short stalks Geomyces pannorum Blastomyces dermatitidis

39 Order onygenales Colony morphology:
cinnamon-brown in centre, some conidia on swollen hyphal cells white to cream in centre, conidia NOT on swollen hyphal cells Myceliopthora thermophila Chrysosporium keratinophilum

40 dematiaceous hyphomycetes
Conidial forms: Single-celled conidia Multi-celled conidia

41 dematiaceous hyphomycetes
Colony morphology: mucoid, white or pale pink turning dark later floccose or velvety, brown-olive colour

42 dematiaceous hyphomycetes
Conidia morphology: conidia produced in clusters on the sides of the hyphae conidia produced in terminal rosettes on denticles Aureobasidium pullulans Sporothrix schenkii

43 dematiaceous hyphomycetes
Conidia morphology: conidia produced in chains conidia NOT in chains

44 dematiaceous hyphomycetes
Conidia chain length and form: conidia chains long and rarely branching conidial chains short and heavily branched

45 dematiaceous hyphomycetes
Growth requirements: no growth or very poor growth at 37 C good growth at 37 C and 40 C Cladeophialophora carrionii Cladeophialophora bantiana

46 dematiaceous hyphomycetes
Conidial wall texture conidia rough-walled conidia smooth-walled Cladiosporium herbarum

47 dematiaceous hyphomycetes
Conidial shape: Most conidia round Most conidia oval or lemon shaped Cladosporium sphaerospermum

48 dematiaceous hyphomycetes
Conidial chain length: conidial chains very short and compact conidial chains longer, more divergent Fonsecaea pedrosi Cladosporium cladosporioides

49 dematiaceous hyphomycetes
Conidia morphology: conidia elongate, less than 2 microns wide conidia broadly oval, more than 2 microns wide Rhinocladiella atrovirens Rhinocladiella mackenziei

50 dematiaceous hyphomycetes
Conidia cellularity: conidia all two-celled and thin-walled conidia with more than two cells Ochroconis gallopava

51 dematiaceous hyphomycetes
Conidia septa: some conidia with oblique or longitudinal septa in addition to transverse septa conidia with transverse septa only

52 dematiaceous hyphomycetes
Conidia morphology: conidia in chains, most often > 3, most conidia with apical beak conidia formed singly or in chains of 2-3, mostly without a beak Alternaria alternata Ulocladium chartarum

53 dematiaceous hyphomycetes
Conidia morphology: Conidia oval or asymmetrical Conidia symmetrical Curvularia lunata

54 dematiaceous hyphomycetes
Conidial septa and hila: conidia oval with many septa and strongly protruding hila conidia oval with few septa and hila not protruding

55 dematiaceous hyphomycetes
Number of septa: conidia mostly with three septa conidia mostly with five septa Bipolaris hawaiiensis Bipolaris australiensis

56 dematiaceous hyphomycetes
Conidia morphology: conidia NOT widest near the base, some worth projections on conidia walls conidia widest near the base Exserohilum mcginisii

57 dematiaceous hyphomycetes
Conidia morphology: conidia with basal septum only darker than the others conidia with both the basal septum and apical septum dark Exserohilum rostratum Exserohilum longistratum

58 moulds with chains of dry conidia arising from phialides
Presence of vesicles at the tip of conidiophore stalk Absent Present

59 aspergillus species complexes
Colony colour: Not green Some shade of green

60 aspergillus species complexes
Vesicle shape: vesicles rounded elongated vesicle (>100 microns long) Aspergillus clavatus

61 aspergillus species complexes
Colony morphology: Colony dark green, sometimes with yellow areas, stalks smooth colony uniformly yellow-green, stalks rough Aspergillus flavus

62 aspergillus species complexes
Presence of metulae (cell layer between vesicle and spore-forming phialides) present absent

63 aspergillus species complexes
Distribution of phialides Over entire surface of large, round vesicle Over upper two-thirds of small flattened vesicle Aspergillus fumigatus Aspergillus glaucus

64 aspergillus species complexes
Colony morphology Stalks colourless, heads globose or irregular stalks pale brown, heads columnar in old cultures Aspergillus nidulans Aspergillus versicolor

65 aspergillus species complexes
Colony morphology Stalks rough, colony orange brown Stalks brown or yellow Stalks colourless Aspergillus ochraceus

66 aspergillus species complexes
Colony colour yellow to buff dull grey to charcoal Aspergillus ustus Aspergillus flavipes

67 aspergillus species complexes
Colony colour: black or dark brown cinnamon-brown to sand-coloured white or pale cream Aspergillus niger Aspergillus terreus Aspergillus candidus

68 other chain-forming enteroblastic moulds
Colony colour: colony green colony not green Penicillium spp

69 other chain-forming enteroblastic moulds
Conidia morphology: conidia large, round, with a flat scar conidia small, oval, with a minute scar Scopulariopsis brevicaulis

70 other chain-forming enteroblastic moulds
Conidia colour: colony pale purple colony greenish-buff Purpureocillium lilacinum Paecilomyces variotti

71 moulds with wet conidia adhering in masses
Colony colour: white, grey, pink OR red colonies brown OR black colonies

72 moulds with wet conidia adhering in masses
Colour of old colonies: remain white or pink without brown pigment develop dark pigment

73 moulds with wet conidia adhering in masses
Presence of macroconidia: present absent (only unicellular microconidia present)

74 moulds with wet conidia adhering in masses
Macroconidia morphology: macroconidia straight with round ends macroconidia curved with pointed ends Fusarium lichenicola

75 moulds with wet conidia adhering in masses
Macroconidia morphology: macroconidia mostly two-celled macroconidia on polyphialides Fusarium dimerum Fusarium semitectum

76 moulds with wet conidia adhering in masses
Microconidia arrangement: microconidia on short phialides microconidia on long phialides

77 moulds with wet conidia adhering in masses
Microconidia morphology: microconidia elongated, some forming chains microconidia ovoid to kidney-shaped, not in chains Fusarium proliferatum or Fusarium verticilloides Fusarium oxysporum

78 moulds with wet conidia adhering in masses
Conidia size: conidia mostly wider than 2 microns conidia narrower than 2 microns Fusarium solani Acremonium strictum

79 moulds with wet conidia adhering in masses
Colony morphology: colonies mostly glabrous (at least near the edge) colonies mostly floccose

80 moulds with wet conidia adhering in masses
Phialide morphology: long and tapering reduced to short outgrowths of hyphal cells short annelids with swollen bases Acremonium kiliense or Phaeoacremonium parasiticum Lecythophora mutabilis Scedosporium prolificans

81 moulds with wet conidia adhering in masses
Conidia size: conidia large, microns long conidia smaller, microns long Scedosporium apiospermum Phaeoacremonium parasiticum

82 moulds with wet conidia adhering in masses
Presence of collarettes on conidiogenous cells: distinct collarettes present collarettes absent

83 moulds with wet conidia adhering in masses
Collarette morphology: minute and cylindrical flared or reflexed cup-shaped or funnel-shaped Phaeoacremonium parasiticum Pleurostomophora richardsiae Phialophora verrucosa

84 moulds with wet conidia adhering in masses
Presence of two-celled yeasts: two-celled yeasts abundant; large annellidic pegs two-celled yeasts absent, minute annellidic pegs Hortaea werneckii

85 moulds with wet conidia adhering in masses
Conidia arrangement: branched conidiophores of thick-walled segments conidia borne on sides of hyphae, or on simple branches conidia borne on short annelids with swollen bases Exophalia spinifera Scedosporium prolificans

86 moulds with wet conidia adhering in masses
Growth features: grows at 40C; nitrate test negative (some conidia formed without obvious annellidic pegs) no growth at 40C, nitrate test negative (annellidic pegs visible) Exophalia dermatitidis Exophalia jeanselmei

87 Sporulation on Sabouraud’s Dextrose Agar
mucoraceous moulds Sporulation on Sabouraud’s Dextrose Agar Yes No

88 Colony morphology and growth:
mucoraceous moulds Colony morphology and growth: colonies floccose, rapid growth at 37C colonies floccose, no growth at 37C colonies membranous and waxy, slow growing

89 mucoraceous moulds Spore formation: spores produced outside a vesicle
spores produced inside a sporangia Cunninghamella bertholletiae

90 Sporangia morphology:
mucoraceous moulds Sporangia morphology: sporangia with funnel-shaped bases sporangial base narrowing abruptly to a stalk Lichtheimia corymbifera

91 stalks with a few side branches
mucoraceous moulds Stalk morphology: stalks with a few side branches stalks unbranched

92 Branching of sporangia
mucoraceous moulds Branching of sporangia one or two small sporangia just under main sporangia branches more widely spaced, often curved Rhizomucos pusillus Mucor circinelloides

93 mucoraceous moulds Colony morphology:
colony 3-5mm deep, sporangia grey colony filling the plate air space, sporangia black Rhizomucos pusillus

94 Stalk and spore morphology:
mucoraceous moulds Stalk and spore morphology: stalks about 500 microns long, spores 4-6 microns stalks over 1000 microns long, spores 6-8 microns Rhizopus microsporus Rhizopus arrhizus

95 Sporangia morphology and Presence of Rhizoids:
mucoraceous moulds Sporangia morphology and Presence of Rhizoids: sporangia black, rhizoids prominent at base of stalk sporangia pale or brownish, rhizoids absent Rhizopus stolonifer

96 some stalks with chlamydospores
mucoraceous moulds Colony colour colonies pale yellow colonies pale brown, some stalks with chlamydospores Mucor hiemalis Mucor racemosus

97 mucoraceous moulds Spore morphology: spores without conical papillae
spores with conical papillae Basidiobolus ranarum Conidiobolus coronatus

98 mucoraceous moulds Nature of spores:
motile zoospores produced in liquid culture mucoraceous sporangia produced on special media Pythium spp.

99 Sporangia morphology:
mucoraceous moulds Sporangia morphology: sporangia on funnel-shaped bases sporangia with apical tubular extensions sporangia round, rupturing without leaving a columella Apophysomyces elegans Saksenaea vasiformis Mortierella wolfii

100 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Production of fruiting bodies: within 2 weeks after 2 weeks fruiting bodies absent

101 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Fruiting body morphology: pale-walled fruiting bodies dark-walled fruiting bodies

102 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Colony colour: colonies white to buff coloured colonies dark purple Aphanoascus fulvescens Monascus ruber

103 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Fruiting body morphology: thick-walled ascocarps, covered in long brown hyphae Pycnidia, with thin smooth walls Chaetomium spp. Phoma herbarum

104 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Fruiting body morphology: loose network of dark hyphae flattened, pale-coloured with gills black, with a definite wall Myxotrichum deflexum Schizophyllum commune

105 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Fruiting body morphology: thick-walled ascocarps, containing asci Pycnidia, with thin smooth walls

106 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Ascospore morphology: large, mostly five-celled small, two-celled, ascocarp wall of interlocking plates long, flexuous, with tapered ends Leptosphaeria senegalensis Neotestudina rosatii Piedraia hortae

107 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Conidia morphology: conidia large, two-celled when mature conidia small, one-celled, pycnidia with spines Lasiodiplodia theobromae Pyrenochaeta romeroi

108 moulds that produce macroscopic fruiting bodies
and miscellaneous moulds Colony morphology: colony flat or folded, velvety, with diffusing brown pigment colony domed, densely floccose, without diffusing pigment Madurella mycetomatis Madurella grisea group

109 identification of yeasts
Colony morphology: minute colonies on glucose peptone agar pink or red colonies on glucose peptone agar white or cream colonies on glucose peptone agar presumptive Rhodotorula spp OR Sporobolomyces spp presumptive Malassezia furfur

110 identification of yeasts
Germ Tube test: positive negative Candida albicans Candida dubliniensis Candida africana

111 identification of yeasts
Presence of capsule: present absent presumptive Cryptococcus spp.

112 identification of yeasts
Urease test: positive negative presumptive Cryptococcus spp. OR Trichosporon spp OR Malassezia pachydermatis

113 identification of yeasts
Presence of chlamydospores on cornmeal agar: present negative Candia albicans Candida dubliniensis

114 identification of yeasts
Presence of arthrospores on cornmeal agar: present negative

115 identification of yeasts
Presence of budding cells on cornmeal agar: present negative dichotomously branching hyphae present presumptive Trichosporon spp OR Saprochaete capitata Geotrichum candidum

116 identification of yeasts
Pseudohyphae present: present negative presumptive Candida spp

117 Neoscatylidium dimidiatum
Microscopic Features Macroscopic Features dy/dx: clinical significance skin and nail infections among immigrants from the tropics and sub-tropics. Not contagious (unlike dermatophytosis)