Introduction of Bordetella
Bordetella was described by Bordet and Gengou (1900) in a sputum sample of children with whooping cough. B. pertussis is the causative agent of pertussis or whooping cough.
In 1906 –B. pertussis ( Whooping cough)
1911 – B. bronchoseptica from dog
1937 – B. parapertussis ( mild whooping cough)
Morphology of Bordetella
Gram- ve coccobacilli, 1-1.5 × 0.5 μm, may occur singly or in the chain and may show bipolar staining, non – motile, non – sporing, and capsulated.
B. parapertussis :Non- motile , Gram -negative bacilli.
B.bronchoseptica: similar with B. pertussis except it is motile.
B. pertussis: Same as parapertussis
Pathogenicity of Bordetella
Whooping cough due to irritation caused by endotoxin
The incubation period is most commonly 7 to 10 days.
- Lung damage with emphysema ( Pathological accumulation of air in tissue and organs.)
- Bronchopneumonia and bronchiectasis
- Subconjunctival hemorrhage
1 – Heat labile toxin: causes vasoconstriction in the respiratory tract.
2- Tracheal cytotoxin ( CTC): derived from peptidoglycan of cell wall which inhibits DNA synthesis in ciliated cells.
3- Endotoxin LPS:
4- Pertussis toxin (PT): controlled by PT gene. Mol. wt. 117000, stimulates cyclic AMP pathway, leading to over secretion.
5- Adenylate cyclase ( AC):
- Present on the surface of the B. pertussis cell wall.
- Inhibits the phagocytic activity of the host cell.
Enzyme enters into the cell and gets activated by a mammalian protein called- Calmodulin. Activated A adenylate cyclase induces a high level of intracellular CAMP which impairs the bactericidal activity of polymorphonuclear neutrophil ( PMN) and Macrophages.
6- Haaemolysin: cause hemolysis
7- Filamentous haemagglutination: Agglutination to RBC is inhibited by cholesterol shake culture does not cause filamentous haemagglutination.
Laboratory diagnosis of Bordetella
Specimen: B.pertussis colonizes the ciliated epithelial cells in the upper and lower respiratory tract. A culture specimen should therefore be obtained from the surface of the respiratory epithelial cells of the upper respiratory tract. Specimens obtained from the throat, sputum, or anterior nose that are not lined with ciliated epithelium are not adequate.
Nasopharyngeal swab or aspiration
Asking patients directly to cough into the selective medium.
Direct microscopic examination :
Gram’s stain: Gram-negative bacilli as described above.
Transportation Medium: Transferred to Casamio acid solution at pH 7.2 in modified Stuarts medium Glycerin potato blood agar Bordet Gengou. The addition of penicillin is more selective.
Cephalexin Charcoal Blood Agar
Bordet- Gengou’s medium
2-6 days incubation at 37°C
Small, raised, shiny
Mercury or dewdrop appearance
species Motility, Blood agar, Urea, Oxidase, Catalase
B.pertussis – – – + +
B.parap – + +/24h – +
B.bronchoseptica + + +4h + +
Based on common surface antigen, there are 3 serotypes of B. pertussis.
Suitability of IgM, IgA, and IgG antibodies for diagnosis
Detection of B. pertussis by PCR
Antimicrobial Sensitivity Testing (AST)
Following antibiotics are useful for AST-
Pertussis is a very contagious disease that causes uncontrollable coughing with little or no fever. The coughing may be so severe that it leads to vomiting and aspiration. Whooping cough is predominantly a pediatric disease. It is common in the first year of life and maternal antibodies are not protective. It is worldwide in distribution. Epidemics occur periodically. In the early stage of infection droplets and fomites contaminated by oropharyngeal secretion are infective. Nonimmune easily catches the infection and household contacts at risk. B. pertussis is only responsible for 95 % of cases, B. parapertussis , 5%, and B. brochoseptica occasionally occur. Sometimes adenovirus, Mycoplasma pneumoniae may mimic whooping cough.
Prevention of Bordetella
In view of the high incidence and severity of the new-born disease, it is advisable to start immunization as soon as possible. Three injections at intervals of 4-6 weeks should be given before the age of six months, followed by a booster at the end of the first year of life. Children under four years of age who are patient contacts should receive a booster even if they have been previously immunized.
Vaccine: Diphtheria Pertussis and Tetanus (DPT)