Bordetella pertussis Flashcards
Bordetella pertussis Disease
Whooping cough (pertussis).
Habitat of Bordetella pertussis
Habitat is the human respiratory tract.
Transmission of Bordetella pertussis
Transmission is via respiratory droplets.
Characteristics of Bordetella pertussis
Small gram-negative rods
Laboratory Diagnosis of Bordetella pertussis
1_ Gram-stained smear plus culture on Bordet-Gengou agar.
2_ Identified by biochemical reactions and slide agglutination with known antisera.
3_ PCR tests, if available, are both sensitive and specific.
4_ Serologic tests for antibody in patient’s serum not useful.
Treatment of Bordetella pertussisBordetella pertussis
Azithromycin.
Prevention Bordetella pertussis
1_The acellular vaccine containing pertussis toxoid and four other purified proteins is recommended rather than the killed vaccine, which contains whole organisms.
2_Usually given to children in combination with diphtheria and tetanus toxoids (DTaP). 3_Azithromycin is useful in unimmunized people who are known to be exposed.
Pathogenesis of Bordetella pertussis
1Pertussis toxin stimulates adenylate cyclase by adding ADP-ribose onto the inhibitory G protein.
2 Toxin has two components:
**subunit A, which has the ADP-ribosylating activity, and
**subunit B, which binds the toxin to cell surface receptors.
3_ Pertussis toxin causes lymphocytosis in the blood by inhibiting chemokine receptors.
4_ Inhibition of these receptors prevents lymphocytes from entering tissue, resulting in large numbers being retained in the blood.
5_ Inhibition of chemokine receptors occurs because pertussis toxin ADPribosylates the inhibitory G protein which prevents signal transduction within the cell.
6_In addition, extracellular adenylate cyclase is produced, which can inhibit killing by phagocytes.
7_Tracheal cytotoxin damages ciliated epithelium of respiratory tract.
