Bordetella pertussis - Whooping cough

The organism enters the respiratory tract after inhalation and destroys the ciliated epithelial cells of the trachea and bronchi through various toxins. If strong clinical suspicion of whooping cough, refer to microbiology for a pernasal swab for immediate processing to improve isolation rates of B. pertussis

About

• The whoop is the sudden inspiration heard at the end of a bout of coughing
• Prevented by immunisation with DTP (triple vaccine)

Aetiology

• Infection caused by Bordetella pertussis
• Similar infections caused by Bordetella parapertussis
• Short incubation period of 1-2 weeks
• Appears to destroy cilia

Toxin producing

• Pertussis toxin: that activates host cell production of cAMP to modulate cell protein synthesis regulation, a tracheal cytotoxin that causes destruction of ciliated epithelial cells, and a cell surface hemagglutinin to assist in bacterial binding to the host cells.
• Adenylate cyclase toxin

Characteristics

• Small coccobacillus. Gram-negative
• Obligate aerobes with fastidious growth needs
• Non-motile and non capsulated

Source

• Human reservoir only

Clinical

• Coryza type illness
• Chronic worsening severe bouts of paroxysmal coughing
• Apneic episodes esp < 6 months and Neurological damage
• Bronchiectasis, cyanosis and lobar collapse

Investigations

• Pernasal swabs and culture on Bordet-Gengou agar

Sensitivity

• Erythromycin

Management

• Refer those at risk under 6 months
• Inform infectious diseases consultant - Notifiable disease
• Azithromycin 500mg OD For 3 days
• Treat unimmunised contacts e.g. siblings