Bordetella pertussis

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Bordetella pertussis
By
Dr. Emad AbdElhameed Morad
Lecturer of Medical Microbiology and Immunology
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Morphology

• Gram negative capsulated cocco-bacilli.

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Cultural characters

• Grows on complex enriched media like
• Cephalexin charcoal blood agar
• Bordet-Gengou medium (potato-blood-glycerol
  agar)
• Colonies appear after 3-7 days. They are greyish
  white in color with shiny convex surface (mercury
  drop).

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Biochemical reactions
Oxidase positive
Urease negative
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Virulence factors

• Filamentous hemagglutinin (FHA) mediates
  adherence to the cilia of the epithelial cells of
  trachea and bronchi.
• Fimbriae and pertactin help adhesion.
• Pertussis toxin (PTx) irritates and damages the
  ciliated cells of the respiratory tract.
• Tracheal cytotoxin similar to pertussis toxin.
• Endotoxin.
• Adenylate cyclase inhibits the phagocytes.

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Whooping cough

• It is mainly a disease of children.
• Infection occurs by inhalation.
• Incubation period 2 weeks
• Catarrhal stage mild coughing and sneezing.
• Toxemic stage series of severe paroxysmal cough
  that end with an inspiratory whoop.
• Cough may be followed by vomiting, cyanosis and
  convulsions.
• The disease may be complicated by
  subconjunctival hemorrhage.

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Whooping cough
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Laboratory diagnosis

• Specimen nasopharyngeal secretions obtained by
  pernasal swabs or cough plate.

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• Culture is positive during catarrhal stage. The
  swab is inoculated on Bordet-Gengou medium for 7
  days.
• Direct detection of the organism in the
  specimen
• Immunofluorescence
• PCR
• Serological detection of antibodies which start
  to appear after 3 weeks by
• Agglutination
• ELISA

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Treatment

• Erythromycin is the drugs of choice.

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Prophylaxis

• Heat killed vaccine is given in combination
  with diphtheria and tetanus toxoid (DTP vaccine).
  It is given to children at 2, 4, 6 months and a
  booster dose at 18 months and another booster
  dose at school entry. Adults should not receive
  pertussis vaccine because it may cause
  encephalopathy if given after 6 years.
• Acellular vaccine prepared from 5 antigens
• FHA
• Inactivated PTx
• Pertactin 2 types of fimbriae.
• It is given with diphtheria and tetanus toxoids
  (DTaP).

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GOOD LUCK