Selection of variants of the TEM-1 beta-lactamase, encoded by a plasmid of clinical origin, with increased resistance to beta-lactamase inhibitors.
A TEM-1 derived variant beta-lactamase with increased resistance to beta-lactamase inhibitors was selected in vitro. The variant beta-lactamase was obtained from the parent strain Escherichia coli J62-2 containing resistance plasmid R1 which encodes the TEM-1 beta-lactamase. The variants were obtained by repeated subculture of E. coli J62-2 (R1) for five days in the presence of sub-inhibitory concentrations of amoxycillin plus clavulanic acid. Comparison of this variant beta-lactamase with a clinically isolated TEM derived beta-lactamase, with increased resistance to beta-lactamase inhibitors, suggests that they are the same enzyme. Both beta-lactamases have the same pI at 5.25 and have similar ID50 values for the beta-lactamase inhibitors clavulanic acid, sulbactam and tazobactam.
Department of Medical Microbiology, Medical School, University of Edinburgh, UK.
C J
CJ
Thomson
S G
SG
Amyes
D000658:Amoxicillin / Q000494:pharmacology; D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology; D003227:Conjugation, Genetic; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007525:Isoelectric Focusing; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010397:Penicillanic Acid / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics*; D015183:Restriction Mapping; D013407:Sulbactam / Q000494:pharmacology; D000078142:Tazobactam; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000032:analysis / Q000235:genetics*
D002969:Clavulanic Acids; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; D000658:Amoxicillin; D010397:Penicillanic Acid; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1; D013407:Sulbactam; D000078142:Tazobactam