title: Principal beta-lactamases responsible for resistance to beta-lactam antibiotics in urinary tract infections.
abstract: Two independent surveys have been conducted to determine the prevalent bacterial species and beta-lactamase types present in clinical populations of gram-negative, ampicillin-resistant isolates. A total of 208 isolates (112 from Nottingham Hospital and 96 from Charing Cross Hospital), all of which had been collected from out-patients suffering from urinary tract infections, were investigated. The incidence of ampicillin-resistant isolates (minimum inhibitory concentrations, 8 micrograms/ml) was 24.1% and 18.8% within the Nottingham and Charing Cross samples, respectively. The surveys gave similar results within the ampicillin-resistant samples. Escherichia coli was the prevalent bacterial species (52.9%), followed by Klebseilla pneumoniae (30.3%). The majority of isolates, at least 54.8% and possibly as high as 74.5%, owed their principal beta-lactamase activity to enzymes mediated by R-plasmids. The most prevalent beta-lactamases were TEM-1 (53.3%), SHV-1 (30.9%), and OXA-1 (11.5%). Positive associations were found between E. coli and TEM-1 or OXA-1 and between K. pneumoniae and SHV-1.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology* / Q000627:therapeutic use; D001419:Bacteria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D002876:Chromosomes, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006801:Humans; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics; D010403:Penicillin Resistance; D011815:R Factors; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000382:microbiology*; D001618:beta-Lactamases / Q000502:physiology*
chemical_list: D000667:Ampicillin; D001618:beta-Lactamases