Global perspective on antimicrobial resistance in Haemophilus influenzae.

The prevalence of plasmid mediated beta-lactamase production among clinical isolates of Haemophilus influenzae has increased steadily since first recognized in 1973, nationwide surveillance studies were conducted in the USA in 1983-1984, 1986, and again in 1987-1988. The 1986 study indicated that the overall rate of beta-lactamase production was 20.0% (31.7% among the serotype b isolates). The second USA study also documented strains with resistance to chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, rifampin, erythromycin and certain older cephalosporins. Surveillance studies performed at about the same time in canada, Europe and the United Kingdom, and several Asian countries also documented high rates of beta-lactamase production and other resistance mechanisms among H. influenzae clinical isolates. Resistance to chloramphenicol and tetracycline was documented frequently in European and Asian isolates. Perhaps of greatest concern has been the isolation of H. influenzae (both serotype b and unencapsulated strains) in the USA, Europe, and Asia which possess multiple antimicrobial resistance mechanisms.