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11 Cards in this Set

  • Front
  • Back
What disease does B. pertussis cause?
Pertussis or whooping cough
How is B. pertussis diagnosed?
Bacterial culture(on Bordet-Gengou agar), polymerase chain reaction or serology.
What are the three stages of whooping cough?
1. Catarrhal(1-2 weeks with symptoms similar to a viral URI, most contagious stage.
2. Paroxysmal, following one to six weeks with characteristic burst of cough with respiratory whoop.
3. Convalescent(2-3 weeks with decreased coughing attacks; not contagious.
What are the virulence factors of B. pertussis?
Attachment virulence factors(filamentous hemagglutinin) and toxins(pertussis toxin, tracheal cytotoxin and invasive adenylate cyclase.
What is the mechanism of action of filamentous hemagglutinin(FHA)?
FHA facilitates attachment to the cilia of respiratory epithelial cells.
What is the mechanism of action of tracheal cytotoxin?
Ciliostasis and epithelial cell death diminishing mucociliary clearance.
What is the mechanism of action of invasive adenylate cyclase and pertussin toxin?
Invasive adenylate cyclase increases cycline adenosine monophosphate(cAMP). Pertussis toxin also increases cAMP by inactivating G1 via adenosine diphosphate(ADP) ribosylation. Inactivated G1 cannot inhibit adenylaye cyclase.
What is the clinical significance of increased cAMP?
Impairs cell function(especially neutrophils, macrophages, lymphocytes) and chemotaxis. Impaired chemotaxis leads to lymphocytosis because lymphocytes stay in circulation instead of migrating into lymphoid tissue.
What is the treatment for whooping cough and when should it be given?
Macrolides(azithromycin), should be given in the prodromal or catarrhal stage to render the patients noninfectious. However, treatment does not alter the clinical course of the disease.
The majority of whooping cough cases occur in whom today?
Classically, unimmunized infants younger than 1 year. However, in the last 10 years adolescent and adult infections are more common than infant infections.
What vaccines are available for B. pertussis?
A killed whole cell vaccine and an acellular vaccine are available for children under 7 years. Two booster vaccines are also available for adolescents and adults.