Gram-negative (see GRAM’S STAIN), rod-like, aerobic, non-sporing and non-motile parasitic bacteria. Mostly found in the respiratory tract, they may be part of the normal ?ora, but may also be responsible for several diseases. The main pathogenic species of haemophilus is H. in?uenzae, which may cause severe exacerbations of chronic BRONCHITIS, as well as MENINGITIS, EPIGLOTTITIS, SINUSITIS, and otitis media (see EAR, DISEASES OF). Other species may cause conjunctivitis (see EYE, DISORDERS OF) or CHANCROID. Haemophilus species are sensitive to a wide range of antibiotics, though generally resistant to penicillin. Infants are routinely immunised with Haemophilus B vaccine to prevent meningitis, septicaemia and epiglottitis
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