32. Bordetella (Bordetella pertussis, Bordetelal parapertussis). Morphology, biology, pathogenic factors. Pathogenesis and immunity of whooping cough and other diseases. Microbiological diagnosis. Specific prophylaxis and therapy. Haemophilus spp. Morphology, biology, antigenic structure. Pathogenic factors. Disease and immunity. Microbiological diagnosis. Specific prophylaxis and therapy. Listeria monocytogenes. General characteristics.

General Characteristics

• Gram status: Gram-negative coccobacilli
• Oxygen requirement: Obligate aerobes
• Motility: Non-motile
• Capsulated: Yes (small capsule)
• Spores: Non-spore forming
• Growth needs: Highly fastidious → Requires enriched medium (e.g. Bordet-Gengou agar or Regan-Lowe agar)
• Fermentation: Forms acid (not gas) from glucose and lactose
• Temperature: Grows at 35–37°C with prolonged incubation

Epidemiology

• Reservoir: Humans (strictly human pathogen)
• Transmission: Airborne respiratory droplets (especially during paroxysmal stage)
• Target: Primarily infants and unvaccinated children
• Incubation period: 7–10 days

Pathogenesis

1. Colonization of upper respiratory tract ciliated epithelium via adhesins
2. Toxin production damages epithelial cells → Impaired mucociliary clearance
3. Tracheal cytotoxin kills cilia-bearing cells → intense coughing
4. PT disrupts immune signaling → systemic symptoms
5. Persistent infection leads to accumulation of mucus and intense paroxysmal coughing

Clinical Features of Pertussis (3 stages)

1. Catarrhal stage (1–2 weeks)

• Cold-like symptoms: rhinorrhea, low-grade fever, mild cough
• Highly contagious

2. Paroxysmal stage (2–6 weeks)

• Paroxysms of intense coughing (up to 50 times/day)
• Whooping sound (high-pitched gasp) after fits
• Post-tussive vomiting, cyanosis possible

3. Convalescent stage (weeks–months)

• Gradual recovery, secondary infections may occur
• Cough may persist