Haemophilus influenzae animated Haemophilus influenzae infections

Haemophilus influenzae appearance

  • small, pleomorphic, Gram-negative coccobacilli or rods
  • nonmotile
  • non-spore forming
  • some strains possess a polysaccharide capsule; these strains are serotyped into 6 different types (a-f)
  • the organism may appear Gram-positive unless the Gram stain procedure is very carefully carried out

Infections caused by Haemophilus influenzae bacteria

Haemophilus influenzae (including Hib) is a bacterium that can cause a severe infection, occurring mostly in infants and children younger than five years of age. In spite of its name, H.influenzae does not cause influenza (the "flu"). It can cause lifelong disability and be deadly. There are six identifiable types of Haemophilus influenzae bacteria (a through f) and other non-identifiable types (called nontypeable). The one that most people are familiar with is Haemophilus influenzae type b, or Hib. There’s a vaccine that can prevent disease caused by Hib, but not the other types of H.influenzae.

  • Pneumonia
  • Bacteremia
  • Meningitis
  • Epiglotitis
  • Eye infections (conjunctivitis)
  • Sinusitis
  • Cellulitis
  • Infectious arthritis

Deaths caused by Haemophilus influenzae (2004)

  • Worldwide incidence:
    2,000,000–3,000,000 [1]
  • Worldwide deaths:
    386,000 [2]

Haemophilus influenzae treatment
Should be always guided by in vitro susceptibility tests!!
Selection of appropriate antibiotics depends on diagnosis!!

  • ampicillin
  • amoxicillin
  • ampicillin/sulbactam
  • amoxicillin/clavulanate
  • cefuroxime
  • ceftriaxone
  • cefotaxime
  • Trimethoprim-Sulfomethoxazole(TMP-SMX)
  • azithromycin
  • clarithromycin
  • doxycicline

Haemophilus influenzae vaccination




Textbook of bacteriology

Colony appearance

Haemophilus influenzae morphology Hib cell morphology Haemophilus influenzae Gram stain