Bordetella is a genus of gram negative coccobacilli, which are encapsulated. They are non-motile except B. bronchiseptica and are obligate aerobes except B. petrii. They are highly fastidious.
Pathogenesis
Route of entry
Bordetella infects only humans and is transmitted by air borne droplets.
- Capsule is antiphagocytic
- Organism produces pigment
- Hemaggluttinin, facilitates attachment to the cilia of the epithelial cells of the respiratory tract.
- Adenylate cyclase is taken up by phagocytic cells and inhibits their bactericidal activity.
- Pertussis-toxin inhibits signal transduction by chemokine receptors, therefore lymphocytes cannot enter lymphoid tissue.
- This stimulates adenylate cyclase by catalyizing ADP-ribosylation of inhibitory submit of G-proteins complex (Gx).
- Toxin also binds to receptors on the surface of the respiratory tract epithelial cells.
Virulence factors • Filamentous hemagglutinin • Pertussis toxin • Adenylate cytotoxin
• Capsule
Predisposing factors • Infants and young children
• Immunocompromised
Clinical symptoms • Whooping cough
• Severe paroxysmal cough (1-4 week)
- Series of hacking coughs
- Massive amounts of mucus
• Leukocytosis up to 70% • Exhaustion due to cough
• Pneumonia
Lab- Diagnosis
Specimen • Nasopharyngeal secretions collected by aspiration
• Per nasal swab
Microscopy • Gram negative coccobacillus • Non-motile
• Capsulated
Bordetella bronchiseptica
Culture
• Strict aerobes
Charcoal cephalexin blood agar
Small pearly grey, shiny, mucoid colonies are formed.
Biochemical tests
• Urease negative • Does not reduce nitrate
• Oxidase positive
Serological tests
• Fluorescent- antibody staining
• PCR
Treatment
- Erythromycin
- Oxygen therapy
- Suction of mucus
Bordetella – howMed
Bordetella is a genus of gram negative coccobacilli, which are encapsulated. They are non-motile except B. bronchiseptica and are obligate aerobes except B. petrii. They are highly fastidious.
Pathogenesis
Route of entry
Bordetella infects only humans and is transmitted by air borne droplets.
Virulence factors • Filamentous hemagglutinin • Pertussis toxin • Adenylate cytotoxin
• Capsule
Predisposing factors • Infants and young children
• Immunocompromised
Clinical symptoms • Whooping cough
• Severe paroxysmal cough (1-4 week)
• Leukocytosis up to 70% • Exhaustion due to cough
• Pneumonia
Lab- Diagnosis
Specimen • Nasopharyngeal secretions collected by aspiration
• Per nasal swab
Microscopy • Gram negative coccobacillus • Non-motile
• Capsulated
Bordetella bronchiseptica
Culture
• Strict aerobes
Charcoal cephalexin blood agar
Small pearly grey, shiny, mucoid colonies are formed.
Biochemical tests
• Urease negative • Does not reduce nitrate
• Oxidase positive
Serological tests
• Fluorescent- antibody staining
• PCR
Treatment