Bordetella genus

Question 1

General feature and habitat of Bordetella (pertussis)

Answer 1

Gram –
Coccobacillus
Reservoir- humans

Question 2

Biochemical Properties of Bordetella (pertussis)

Answer 2

Fimbriae (pili)

Fastidious- requires Bordet-Gengou plate

Question 3

Pathogenesis and Virulence Factors of Bordetella (pertussis)

Answer 3

Highly contagious- transmitted by respiratory droplets (mainly from young children)

Binds to respiratory epithelium using specific pili- Filamentous Hemagglutinin Adhesins (FHA) and pertactin (PRN) then releases its toxins

Pertussis toxin (AB type)- acts by ADP ribosylation of Gi causing inhibition of Gi

Leads to increase in cAMP levels (inhibition of inhibitor)

ADP ribosylation of Gi also disables chemokine receptors causing
lymphocytosis (high number of lymphocytes in blood)

Adenylate cyclase toxin- acts as an adenylate cyclase which increases cAMP

Tracheal cytotoxin- part of the peptidoglycan wall (endotoxin), damaging the
ciliated respiratory epithelium causing blockage of mucociliary clearance

Dermonecrotic toxin (AB type)- causing SMC contraction, leading to necrosis

Question 4

Clinical Features of Pertussis

“Whooping Cough”

Answer 4

Stages of Pertussis: (high mortality in developing countries)

1. Prodromal stage (7-10 days)- incubation period
2. Catarrhal stage (1-2 weeks)- normal cough, running nose, very contagious
3. Paroxysmal stage (2 weeks to 1 month)

Characteristic coughing and whooping upon inspiration (in children)

Frequent superinfection (Staph. or Haemophilus causing severe pneumonia)

Weakness, vomiting, cyanosis, pain, hemorrhages, encephalitis

4. Convalescent stage (1 to 3 months)- slow recovery (“100 day’s cough” disease)

Question 5

Diagnosis of Bordetella (pertussis)

Answer 5

Cultivation by coughing into the plate or by using nasal swab

Bordet-Gengou agar (10% blood, glycerol, potato)- 3-7 days, moist environment

Serology- antigen detection by latex agglutination and immunofluorescence (IF)

Question 6

Treatment of Bordetella (pertussis)

Answer 6

Macrolide (i.e. Erythromycin)- prophylactic or when symptoms are mild

Question 7

Prevention of Bordetella (pertussis)

Answer 7

DTPa- Diphtheria, Tetanus and acellular Pertussis (pertussis antigen)