Bordetella pertussis (Whooping cough, croup, pertussis)

General:

Clinical: Primarily children <1yo. Effective vaccine introduced in 1949, though immunity may wane & new strains may be developing. Has a 7-10 day incubation; then catarrhal stage resembling common cold, paroxysmal stage at 1-2wks with "whooping" cough, and convalescent stage at 2-4wks.

• Normal: Not considered a commensal, but is exclusively human with no other known reservoir.
• Abnormal: Organisms attach to ciliated respiratory epithelium, proliferate, and cause local damage & systemic toxicity (pertussis toxin, among others). Attachment is mediated by pertactin (aka P69) and filamentous hemagglutinin; they also cause macrophages to phagocytize without an oxidative burst to destroy them, thus also protecting them from antibody response.

Resistance: Generally sensitive to macrolides.

Morphology: Gram- coccobacilli, very small (0.2-0.5 x 1.0um). Fluorescein-labeled antibodies are used but are true positive only in just over half of cases and false-positives may occur with other organisms.

Growth characteristics: Strictly aerobic, growing best at 35C in humidified chamber over ~7days (tiny colonies appear after ~>3 days. PCR is ~90% sensitive; serology for antibodies against filamentous hemagluttinin and pertussis toxin is also used. Produce pertussis toxin, adenylate cyclase/hemolysin, dermonecrotic toxin, and tracheal cytotoxin. Very sensitive to drying during processing; ideal sample is nasopharyngeal aspirate on something other than cotton swab, in specialized transport medium (such as Regan-Lowe medium).

Common/important pathogens: