title: Ampicillin-resistant Haemophilus influenzae. 1. Incidence, mechanism, and detection.
abstract: Ampicillin resistance in Haemophilus influenzae, an organism once thought to be universally susceptible to ampicillin, is increasing. It varies from one institution or community to another, and rates of 6.6% to 48% have been reported. The vast majority of resistant strains produce beta-lactamase, an enzyme that hydrolyzes the beta-lactam ring of ampicillin and other susceptible beta-lactam antibiotics. The beta-lactamase production is mediated by a gene contained on a plasmid (piece of extrachromosomal DNA). It is important for physicians and microbiologists to be aware that an infection such as meningitis or otitis media could be caused by ampicillin-resistant strain of H influenzae. Knowledge of the incidence of resistance for the institution or community is particularly pertinent in selection of empiric therapy.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D003470:Culture Media; D006192:Haemophilus Infections / Q000188:drug therapy; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D011815:R Factors; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D003470:Culture Media; D000667:Ampicillin; D001618:beta-Lactamases