Bordetella

1. Bordetella
By Dr. Rakesh Prasad Sah
Associate Professor, Microbiology

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.

12. Pertussis Toxin

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

15. Catarrhal Stage
– Maximally infective
– Clinical diagnosis is difficult.

16. Paroxysmal Stage
– Violent spasm of continuous coughing 
followed by a long rush of air into the empty
lungs  with a characteristic of “Whoop”.

17. Convalescent Stage
– Frequency and severity of coughing gradually decreases.

19. Complications
• Subconjunctival hemorrhage due to pressure effects of violent
coughing.
• Bronchopneumonia and lung collapse.
• Convulsions and coma.

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

25. Laboratory Diagnosis

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.