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Van Thi Bao Cao, Guillaume Arlet, Britt-Marie Ericsson, Ann Tammelin, Patrice Courvalin, Thierry Lambert, Emergence of imipenem resistance in Klebsiella pneumoniae owing to combination of plasmid-mediated CMY-4 and permeability alteration, Journal of Antimicrobial Chemotherapy, Volume 46, Issue 6, December 2000, Pages 895–900, https://doi.org/10.1093/jac/46.6.895
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Abstract
Klebsiella pneumoniae BM2974 isolated from an abdominal abcess was resistant to high concentrations of all available β-lactams, including recently developed third-generation cephalosporins and carbapenems. Isoelectric focusing of β-lactamases and amplification, cloning and sequencing of the corresponding genes, together with conjugation and transformation experiments, indicated that, in addition to the chromosomally encoded β-lactamase, the strain produced three plasmid-mediated β-lactamases with pIs of 5.4, 8.2 and 9.0, which corresponded to TEM-1, SHV-5 and AmpC-type CMY-4, respectively. Strain BM2974 also lacked a major outer membrane protein of c. 40 kDa which was present in the spontaneous imipenem-susceptible revertant BM2974-1. We suggest that imipenem resistance in strain BM2974 is attributable to production of CMY-4 β-lactamase combined with permeability alteration.