Bordetella pertussis Study Notes

Bordetella pertussis Overview

  • Obligate human pathogen, non-motile, fastidious coccobacillus.

  • Grows at 35-36ºC and does not produce acid from sugars.

Virulence Factors

  • 6 types of secretion systems involved.

  • Key factors include:

    • Filamentous Haemagglutinin (FHA): Important for adherence, consists of proteolyzed 200 kDa structure.

    • Exotoxins:

    • Pertussis toxin: Affects immune response and promotes colonization.

    • Adenylate cyclase toxin: Raises cAMP, inhibits immune cells.

    • Tracheal cytotoxin: Inhibits ciliated epithelial cell function.

    • Dermonecrotic toxin: Damages host tissues and has potential neurotropic effects.

  • BvgAS Two Component System: Regulates virulence expression, responding to environmental signals.

Whooping Cough - Symptoms and Stages

  • Stage 1 (Catarrhal): Cold-like symptoms; highly communicable for 1-2 weeks.

  • Stage 2 (Paroxysmal): Severe coughing fits with characteristic whoop lasting 1-4 weeks.

  • Stage 3 (Convalescent): Gradual reduction of symptoms; complete recovery takes weeks or months.

Diagnosis and Treatment

  • Diagnosis via culture methods (Regan Lowe agar, Bordet-Gengou), PCR, and serology.

  • Treatment options include azithromycin, erythromycin, clarithromycin, and trimethoprim/sulfamethoxazole.

Transmission and Prevention

  • Highly infectious; 90% transmission rate. Most at risk: unvaccinated infants.

  • Prevention through vaccination: DTP for young children, Tdap for adolescents, adults, and pregnant women.

  • Vaccination during pregnancy recommended to protect newborns until 8 weeks.

Recent Statistics

  • Significant rise in cases; UK reported 14,894 cases in 2024 with 11 deaths.

  • Continued emphasis on vaccination to combat whooping cough resurgence.