TRC-1: emergence of a clavulanic acid-resistant TEM beta-lactamase in a clinical strain.
A novel TEM-derived plasmid-encoded beta-lactamase, resistant to inhibition by clavulanic acid, has been identified in a clinical strain of Escherichia coli found in Scotland. The beta-lactamase gene was carried on an 81-kb plasmid that conferred no other resistances. The novel enzyme conferred resistance to the amoxycillin/clavulanic acid combination on the host bacterium. The beta-lactamase has a pI of 5.25 and lies between the PSE-4 and SAR-1 beta-lactamases on an isoelectric focusing gel. This beta-lactamase has a Mr value of 25,000, similar to the TEM-1 enzyme and a comparable substrate profile. Its most significant difference is that it is inhibited by clavulanic acid 100-fold less efficiently than the TEM-1 enzyme. The enzyme was confirmed to be derived from the TEM enzymes by probing the plasmid DNA with an intragenic gene probe for TEM-1. This is the first report of a clinical bacterium carrying a TEM-enzyme that confers resistance to clavulanic acid combinations and we have designated the beta-lactamase as TRC-1.
Thomson
C J
CJ
Department of Medical Microbiology, Medical School, University of Edinburgh, U.K.
Amyes
S G
SG
D019818:Clavulanic Acid; D002969:Clavulanic Acids / Q000494:pharmacology*; D003227:Conjugation, Genetic; D015342:DNA Probes; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007525:Isoelectric Focusing; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000302:isolation & purification*
D002969:Clavulanic Acids; D015342:DNA Probes; D004269:DNA, Bacterial; D019818:Clavulanic Acid; D004262:DNA Restriction Enzymes; C074522:beta-lactamase TRC-1; D001618:beta-Lactamases