Haemophilus influenzae

Please note: This is for information only.

Refer to local guidelines for treatment recommendations.

  • Gram negative coccobacillus which needs extra nutrients to grow in the laboratory. Can have a capsule or be non-capsulated, presence of capsule particularly type b (Hib) increases virulence.
  • Hib vaccine is offered to all children as part of the routine childhood immunisations. Invasive infections should be notified to public health as young contacts may need protection with vaccine or prophylactic antibiotics.
  • Patients with Hib infections should be isolated in a single room if possible with respiratory precautions for the first 48hrs. Other H. influenzae infections do not require isolation.

Main clinical infections:

Hib – infections include meningitis, epiglottitis, septicaemia, septic arthritis and osteomyelitis. Rarely seen now due to vaccine.

Non-capsulated H. influenzae – lower and upper respiratory tract infections especially in patients with COPD.

Usually sensitive to:


  • Second and third generation cephalosporins
  • Usually sensitive to amoxicillin and chloramphenicol but resistance is seen so these are only used if a sensitive isolate is found.

Non-capsulated H. influenzae:

  • Varying sensitivity to amoxicillin (20% resistance).
  • Co-amoxiclav
  • Doxycycline
  • Quinolones (Ciprofloxacin, levofloxacin)
  • Cephalosporins.

Usually resistant to:

  • Penicillin
  • Erythromycin
  • Vancomycin
  • Metronidazole