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Bordetella Species

• Named after the Belgian bacteriologist Jules Bordet in 1906
• 16 spp (12 cause disease in humans)
• Spp:

NB: spp. in underline = not strictly aerobic

History

• Pertussis, “a violent cough,” AKA whooping cough or “the cough of 100 days,” 1578: described in a Paris epidemic. 1906: B. pertussis isolated 1940’s: Vaccine developed in the 1940s. Before this pertussis was a major cause of infant morbidity and mortality.

| Site | Human URT (we are only reservoir for B.pertussis) | | --- | --- | | Transmission | Airborne droplets | | Risk Factors | <1yrs Children & adolescents Unvaccinated | | Clinical syndromes | NB: Notifiable disease Incubation: 7-10d (range 6-20d)

Features:

• Cough illness lasting >14d
• & 1 of: (a) paroxysmal coughing, (b) inspiratory ‘whoop’ (forceful inspiration after coughing fit; mostly in <5yrs), (c) post-cough vomiting

Phases of illness

1. Catarrhal: Coryza, fever, cough, conjunctival injection (1-2wks)
2. Paroxysmal: paroxysmal cough; afebrile; whoop . Worse at night.
3. Convalescent: slow-resolving cough (months).

Complications:

• Pneumonia
• Encephalopathy & seizures | | Infectious period | 21d post symptom onset, or 48h after ABx started | | Case definitions (UKHSA 2024) | Suspected: new cough +1 or more of: • paroxysms of coughing • post-tussive vomiting • inspiratory whoop • cough of duration 14 days or more

Confirmed: Sx of pertussis + 1 of: • +ve Respiratory sample (NPA/NPS/PNS) • +ve Respiratory PCR • anti-pertussis toxin IgG titre >70 IU/ml (serum) or >70 aU (OF) (NB: in the absence of vaccination in the past year)

Epidemiologically linked: Sx of pertussis & was in close contact with Confirmed case within 21d onset of their cough

(Close contact: Household, overnight stay in same room) | | Risk groups (UKHSA 2024) | Group 1: Vulnerable infants A. Unimmunised infants (born <32wks) <2 months old regardless of maternal vaccine status. B. Unimmunised infants (born >32 weeks) <2 months old whose mothers did not receive pertussis vaccine after 16 weeks & >2 weeks before delivery. C. Infants 2 - 5 months, regardless of maternal vaccination status or gestational age at delivery. D. Infants from 5 - 12 months who aren’t fully vaccinated.

Group 2: Individuals who could transmit to Group 1, and haven’t received vaccine in last 5 years (but >7d ago) A. 32+wks Pregnant women B. HCWs who provide close personal care to Group 1 infants & pregnant women. C. People whose work involves regular, close & prolonged contact with Group 1 infants. D. People who share a household with a Group 1 infant. |

Pathogenic Mechanisms

Lab diagnostics

• Bug:

  • GN coccobacilli 0.2-0.5 x 0.5-2.0µm.
  • Singly, in pairs; rarely in chains
  • Bipolar staining.
  • Motile or non-motile.
  • Aerobic (exceptions: B. petrii, bronchialis, flabilis and sputigena)

• Agar: Aerobic

  • Bordetella medium: Charcoal blood agar + cefalexin
    • B.pertussis grows poorly/not at all on Maconkey, nutrient, blood agar.
  • 35-37 C
  • 5-7d (slow-growing)

• Colony:
  • Smooth, convex, pearly, glistening, nearly transparent - ‘mercury drop’
  • Zone of haemolysis without definite periphery
• Species ID:
  • Locally: Growth on Bordetella media, Gm stain, slide agglutination with antisera.
    • Oxidase: Pertussis/bronchiseptica +, Parapertussis -
    • MALDI: Good for non-classical spp.
  • Pertussis/parapertussis: Refer to Colindale (National Reference Laboratory, Vaccine Preventable Bacteria Section). They will:
    • Confirm ID (PCR, MALDI)
    • Serotype (Surface agglutinogens [1, 2 and 3]:
      • Serotypes 1,2; 1,3; & 1,2,3).
      • Commonest is 1,3 (in UK).