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Babini, Gioia S, Yuan, Meifang, Hall, Lucinda M C and Livermore, David M 
ORCID: https://orcid.org/0000-0002-9856-3703
(2003)
Variable susceptibility to piperacillin/tazobactam amongst Klebsiella spp. with extended-spectrum beta-lactamases.
Journal of Antimicrobial Chemotherapy, 51 (3).
pp. 605-612.
ISSN 0305-7453
Abstract
MICs of piperacillin/tazobactam are conventionally determined by varying the concentration of piperacillin in the presence of a fixed 4 mg/L tazobactam. When tested in this way, the MIC distribution for Klebsiella isolates with extended-spectrum beta-lactamases (ESBLs) is strongly bimodal, such that many producers are inhibited at 16 + 4 mg/L whilst others require MICs of > or =512 + 4 mg/L. When, however, piperacillin/tazobactam was tested as a fixed 8:1 ratio, the MIC distribution became unimodal. If clavulanate 4 mg/L was combined with piperacillin, a unimodal MIC distribution was seen for ESBL-producing Klebsiella spp. but a bimodal distribution arose if the clavulanate concentration was reduced to 0.25 mg/L. These data for alternative combinations suggested that the bimodal MIC distribution seen for piperacillin + tazobactam 4 mg/L was a titration effect, not a reflection of some ESBLs being resistant to tazobactam. Even within single strains, as defined by serotype and DNA fingerprints, there was considerable variation in susceptibility to piperacillin + tazobactam 4 mg/L, with some representatives highly susceptible and others highly resistant. Some of the more resistant representatives produced more of their ESBL, or had a greater number of beta-lactamase types, but these associations were not universal. Elevated resistance to piperacillin + tazobactam was not associated with porin change in any ESBL producer examined, but has been found by others.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | bacterial outer membrane proteins,drug resistance, multiple, bacterial,humans,klebsiella,microbial sensitivity tests,penicillanic acid,piperacillin,beta-lactamases |
| Faculty \ School: | Faculty of Medicine and Health Sciences > Norwich Medical School |
| Depositing User: | Pure Connector |
| Date Deposited: | 24 Jan 2014 12:36 |
| Last Modified: | 24 Oct 2022 05:47 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/46752 |
| DOI: |
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