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.

Carbapenemases: the Versatile β-Lactamases

“…OXA (for "oxacillin-hydrolyzing") ␤-lactamases represented one of the most prevalent plasmid-encoded ␤-lactamase families in the late 1970s and early 1980s (129,132,198). When the molecular class D OXA ␤-lactamases were placed in a separate molecular class from the other serine ␤-lactamases (76), they had been identified mainly in the Enterobacteriaceae and P. aeruginosa (23,144) and were functionally described as penicillinases capable of hydrolyzing oxacillin and cloxacillin (21).…”

β-Lactams and β-Lactamase Inhibitors: An Overview

“…As the result of natural product screening, clavulanic acid with a novel clavam structure (Table 6) was identified as a broad spectrum inhibitor of the staphylococcal penicillinases and most of the recognized plasmid-encoded penicillinases found in enteric bacteria (Reading and Cole 1977;Cole 1982), including the highly prevalent TEM and SHV enzymes (Simpson et al 1980). The TEM blactamase was shown to be inactivated by this suicide inhibitor that initially acylates the active site serine with transient inhibition that includes hydrolysis of the inhibitor before complete enzyme inactivation (Charnas et al 1978;Charnas and Knowles 1981).…”

THE TENTH C. L. OAKLEY LECTURE * : The success of plasmid-encoded resistance genes in clinical bacteria: An examination of plasmid-mediated ampicillin and trimethoprim resistance genes and their resistance mechanisms

“…There have been several surveys of plasmid-encoded B-lactamases, carried by P-lactam resistant gramnegative bacteria, to investigate their relative clinical importance (Simpson et al, 1980(Simpson et al, , 1986Roy et al, 1983;Nandivada and Amyes, 1987;Reid et al, 1988a). Most of these studies have concentrated on bacteria isolated in Europe, though one of them has examined the P-lactamases in clinical bacteria isolated in India (Nandivada and Amyes, 1987).…”