CASE BASED REVIEW OF MEDICAL MICROBIOLOGY
Bordetella pertussis
Dr Tadayo Hashimoto M.D.
Professor
Department of Microbiology & Immunology
What make B. pertussis pathogenic to humans?
- Ability to tolerate and grow at body temperature (37°C or higher temperatures)
- Ability to produce a number of virulence factors only at 37°C
- Produce different types of adhesins which mediates bacterial adherence to ciliated cells in the respiratory tract. The most notably one is filamentous haemoagglutinin (Fha) and Pili
- Pertussis toxin (PT): an A-B type exotoxin which inhibits the function of phagocytes. . Also known as histamine-sensitizing factor, lymphocytosis-promoting factor, or islet-activating protein. This toxin has ADP-ribosylating activity causing elevation of cAMP levels in the affected tissue and is responsible for pronounced lymphocytosis characteristically seen in whooping cough patients. For more specific mode of action of this toxin, see the answer for the next question.
- Bacterial adenyl cyclase (ACase) produced by B. pertussis is taken up by the host cell, activated by Ca dependent calumodulin and elevates intracellular c-AMP level of the host cell.(See the Fig. above)
- Tracheal cytotoxin : a fragment of cell wall peptidoglycan released from B. pertussis causes the death of ciliated cells.
- Endotoxin (LPS of the outer membrane of Gram negative bacteria) induces fever in the host via IL-1 and TNFa.
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