oa Southern African Journal of Epidemiology and Infection - Complexity and diversity of beta-lactamase expression in inhibitor-resistant Escherichia coli from public hospitals in KwaZulu-Natal, South Africa : original research
β-lactamase profiles of 38 inhibitor-resistant Escherichia coli isolates obtained from public hospitals in KwaZulu-Natal, selected on the basis of their resistance profiles to one / more of amoxicillin / clavulanate, ampicillin / sulbactam and piperacillin / tazobactam were analysed. Isolates were subjected to iso-electric focusing, plasmid profile determination, PCR of the different β-lactamase genes and sequencing thereof to detect the possible mechanism / s of inhibitor-resistance. A range of β-lactamases including two inhibitor-resistant TEM β-lactamases (TEM-145 and TEM-146), a plasmid-mediated AmpC-type β-lactamase (CMY-20), OXA-1, TEM-55, SHV-2, CTX-M1 and TEM-1 was detected. Diverse β-lactamase genes and / or enzyme combinations, and plasmid profiles inferred extensive mobilisation of resistance genes. Inhibitor resistance could be attributed to a range of mechanisms including but not limited to inhibitor-resistant TEM β-lactamases, hyper-production of TEM-1, hyper-production of chromosomal AmpC and OXA β-lactamases.
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