Whooping Cough

Question 1

1) classification

Answer 1

Family: Alcaligenaceae
Genus: Bordetella
Species: Pertussis

Spread via airborne
Cytotoxic to the trachea
9 - 10 days incubation period
- whooping sound when person breathes in

Question 2

2) Morphology

Answer 2

• gram-negative coccobacilli
  (Resembling H.influenzae)
• capsulated
• nonmotile

Question 3

3) growth characteristics

Answer 3

• aerobic
• very fastidious
• requires enriched medium
• Bordet-Gengou medium (potato-blood-glycerol agar) containing penicillin G, 0.5 if/ml can be used
• catalase positive
• oxidase positive
• nitrate, citrate and urea negative
• doesn’t require growth factors X and V

Question 4

4) Antigenic structure

Answer 4

• filamentous hemagglutinin (a large surface protein)
• pilli
  These mediate adhesion to ciliated epithelial cells and are essential for tracheal colonization

Question 5

5) virulence factors

Answer 5

Filamentous hemagglutinin

Exotoxins:

• pertussis toxin
• adenylate cyclase toxin (interfere with immune cells)
• tracheal cytotoxin
• dermononecrotic toxin
• heat labile toxin

Endotoxin (LPS)

Question 6

6) diseases

Answer 6

Whooping cough (pertussis)

1) Catarrhal stage
2) Paroxysmal stage
3) Convalescent stage

Question 7

7) microbiological diagnosis

Answer 7

Specimen:

Nasopharyngeal swab, nasal swab or cough droplets

DME:

Direct IFA

Cultures:

Bordet -Gengou medium + penicillin:

Pinpoint, convex, glisten, transparent and pearl-like colonies

Serologic tests:
ELISA

Question 8

8) treatment and prevention

Answer 8

• erythromycin, tetracycline or chloramphenicol is recommended

C E T

• active immunization of children with killed pertussis organisms (usually given as DPT)