Haemophilus influenzae
From DrugPedia: A Wikipedia for Drug discovery
Haemophilus influenzae
It is a non-motile Gram-negative rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe.
| Kingdom | Bacteria |
|---|---|
| Phylum | Proteobacteria |
| Class | Gamma Proteobacteria |
| Order | Pasteurellales |
| Family | Pasteurellaceae |
| Genus | Haemophilus |
| Species | H. influenzae |
| Binomial | Haemophilus influenzae |
Contents |
[edit] Surface Characteristics
A relatively simple antigen consisting of repeating units of 3-β-D ribose-(1-->1)-D-ribitol-5-phosphate.
[edit] Pathogenic Activity
Naturally-acquired disease caused by H. influenzae seems to occur in humans only. In infants and young children, H. influenzae type b (Hib) causes bacteremia, pneumonia, and acute bacterial meningitis. Occasionally, it causes cellulitis, osteomyelitis, epiglottitis, and infectious arthritis. Hib remains a major cause of lower respiratory tract infections in infants and children in developing countries where vaccine is not widely used. Unencapsulated H. influenzae causes ear infections (otitis media), eye infections (conjunctivitis), and sinusitis in children and is associated with pneumonia.
[edit] Virulence
The pathogenesis of H. influenzae infections is not completely understood, although the presence of the capsule in encapsulated type b (Hib), a serotype causing conditions such as epiglottitis, is known to be a major factor in virulence. Their capsule allows them to resist phagocytosis and complement-mediated lysis in the non-immune host. The unencapsulated strains are almost always less invasive, however they can produce an inflammatory response in humans which can lead to many symptoms.
