title: beta-Lactamases in laboratory and clinical resistance.
abstract: beta-Lactamases are the commonest single cause of bacterial resistance to beta-lactam antibiotics. Numerous chromosomal and plasmid-mediated types are known and may be classified by their sequences or phenotypic properties. The ability of a beta-lactamase to cause resistance varies with its activity, quantity, and cellular location and, for gram-negative organisms, the permeability of the producer strain. beta-Lactamases sometimes cause obvious resistance to substrate drugs in routine tests; often, however, these enzymes reduce susceptibility without causing resistance at current, pharmacologically chosen breakpoints. This review considers the ability of the prevalent beta-lactamases to cause resistance to widely used beta-lactams, whether resistance is accurately reflected in routine tests, and the extent to which the antibiogram for an organism can be used to predict the type of beta-lactamase that it produces.
authors.affiliation: Department of Medical Microbiology, London Hospital Medical College, United Kingdom.
authors.forename: D M
authors.initials: DM
authors.lastname: Livermore
mesh_terms: D004755:Enterobacteriaceae / Q000201:enzymology / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000201:enzymology* / Q000235:genetics; D006094:Gram-Positive Bacteria / Q000201:enzymology* / Q000235:genetics; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D001618:beta-Lactamases