Haemophilus

  • Gram negative Bacillus
    • Nonencapsulated form is part of normal respiratory flora
    • Encapsulated form produces suppurative respiratory infection
  • May enter bloodstream in small children & produce
  • Infants < 3/12 have Maternal Ig
  • By 3 years, most children have antibodies
  • Therefore 3/12 – 3 years is risk period
    • Especially 3-18/12
  • Many susceptible to Amoxycillin treatment
  • However some produce ß lactamase
    • Treat with
      • Augmentin (Amoxycillin + Clavulanic acid)
      • Cefotaxime
  • Immunisation now available
    • HIB has ↓ incidence +++
Haemophilus, gram stain of haemophilus influenzae
Gram stain of Haemophilus influenzae. Image by Microman12345, Wikimedia Commons, CC BY-SA 4.0.

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.