2. Introduction
• Bordetella
– Highly infectious
– Very small
– Gram-negative
– Cocobacillus
– First described by Bordet and Gengou in 1906.
• Non fermenter, Family Alcaligenaceae
• Species
– Bordetella pertussis
• Causes whooping cough in children characterized by paroxysmal cough (frequent and
violent coughing that can make it hard for a person to breathe) ending in a high-pitched
inspiratory sound described as “whoop”.
– B. parapertussis
• Causes a milder form of whooping cough.
– B. bronchiseptica
• Pathogen of domestic animals.
3. Morphology
• Is a small, ovoid, 1-1.5 µm x 0.3 µm
• Gram Negative coccobacillus
• Non-motile and non-sporing
• Capsulated
• Bipolar metachromatic granules obs on toulidine blue.
4. Culture
• Obligate aerobe.
• Tempr 350C-360C.
• Fastidious organism does not grow on N.A.
• Req. complex media
– Bordet-Gengou (Glycerol-potato-blood agar)
– I.P. 48-72hrs
• Colonies are
– Small
– Smooth
– Opaque
– Greyish white
– Refractile
– Resembling bisected pearls or mercury drops.
B. pertussis
B. parapertussis
5. • Charcoal Blood agar Regan-Lowe (RL) medium.
• Availabe as both semisolid transport medium and as a solid medium
for the isolation of orgganism.
• Biochemical Reactions
– Biochemically inactive.
– Does not ferment sugars
– Indole +ve
– Reduces nitrates
– Urease +ve
– Citratre +ve
– Oxidase +ve
– Catalase +ve
6. Antigenic Structure
Agglutinogens
• Freshly isolated strains of B. pertussis possess heat labile
Ags associated with the capsule (K-Ags) designated 1 to 14
factors or agglutinogens.
• Promote virulence by helping organisms to attach to respiratory
epithelial cells.
LPS (Lipopolysaccharides)
• Heat stable LPS endotoxin of the cell wall.
• Not protective
• Is common to all smooth strains of all three species of Bordetella.
7. Heat Labile Toxin (HLT)
• +nt in all Bordetellae.
• Pathogenic role is doubtful.
• Is a cytoplasmic protein.
Tracheal Cytotoxin (TCT)
• Derived from peptidoglycan of cell wall.
• +nt in all Bordetellae.
• Damage to respiratory epithelial cells more prone to secondary
infections.
8. Adenylate Cyclase (AC)
• Has ability to enter in the target cells.
• Known as AC toxin (ACT).
• Catalyses the production of cAMP by various cells.
Filamentous Haemagglutinin (FHA)
• Indicates attachment of the bacterium to the ciliated epithelial cells of
respiratory tract.
• Also adheres to erythrocytes.
• Abs against it is protective in nature.
• FHA used in pertussis vaccines along with PT toxoid.
Pertactin
• Is an outer membrane protein (OMP) +nt in virulent strains of B. pertussis.
• Included in acellular vaccines of pertussis.
9. Pertussis Toxin
• Heat labile exotoxin.
• +nt only in B. pertuissis.
• Major virulence factor
– Lymphocytosis producing factor (LPF)
– Histamine sensitising factor (HSF)
– Islet activating protein (IAP)
• Causes profound lymphocytosis pertussis patients.
• Mol wt 1,17,000.
• Has two sub units A (enzymatically active) and B (binding).
• Can be toxoided.
• Major component of acellular pertussis vaccines.
14. Pathogenesis
• Ds of childhood known as “whooping cough” or “pertussis”.
• 95% whooping cough B. pertussis and 5% B. parapertussis
and only 0.1% cases B. bronchiseptica is responsible.
• Sources of infection is the patient in the early stage
• I.P. 1 to 2 weeks.
• MOT droplets
• Ds usually lasts for 6-8weeks.
• Consists of three stages
– Catarrhal
– Paroxysmal
– Convalescent
Each lasts for
approx 2 weeks
20. Laboratory Diagnosis
• Microscopy
– Demonstration of bacilli in respiratory secretions by fluorescent Ab
technique.
• Culture
– Catarrhal Stage bacilli most abundant.
21. Laboratory Diagnosis
• The pernasal Swab
– Swab collected from nasal cavity and pharyngeal wall.
– Sample the posterior nasopharynx using a nasopharyngeal swab (NPS) or
pernasal swab (PNS).
– Inoculated on Bordet-Gengou medium or charcoal blood agar.
22. Laboratory Diagnosis
• The Cough plate method
– Bordet-Gengou culture plate 10-15cm in front of mouth asked to
cough cough droplets directly inoculated into culture medium.
23. • The Postnasal (Peroral) swab
– Postnasal swab is passed through mouth to collect posterior phryngeal
wall secretions.
– Fatty acids +nt in cotton inhibit growth of bacilli better to use dacron
or calcium alginate swabs for collection.
– Swabs are plated without delay.
– Modified Stuart’s medium or charcoal agar used as transport of swabs.
24. • Bordet and Gengou or charcoal blood agar add diamidine,
flouride and penicillin to make media more selective
incubated at 35-360C for 3-5 days. Typical pearl like colonies
of B. pertussis appear in 48-72hrs.
• Confirmed by
– Gram staining G –ve coccobacilli arrange in loose clumps thump print
appearance.
– Slide agglutination with specific antisera.
• PCR
• Serology
– Ab against PT
• Treatment
– Azithromycin
26. Prophylaxis
DPT vaccine
• Dose:- 6,10 and 14 weeks of birth. Booster dose at 16-24months
and at 5 years.
• Route:- I.M. on anteriolateral side of mid thigh.
