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Andreasen MR, Rick T, Alexandersen NR, Hansen KH, Pedersen MS, Warweitzky JK, Botelho CM, Häussler S, Jelsbak L, Schønning K. Identification of a CTX-M-255 β-lactamase containing a G239S substitution selectively conferring resistance to penicillin/β-lactamase inhibitor combinations. J Antimicrob Chemother 2024; 79:810-814. [PMID: 38366372 DOI: 10.1093/jac/dkae033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/18/2024] [Indexed: 02/18/2024] Open
Abstract
OBJECTIVES An Escherichia coli isolate, WGS1363, showed resistance to piperacillin/tazobactam but susceptibility to cephalosporins and contained a previously unrecognized β-lactamase, CTX-M-255, as the only acquired β-lactamase. CTX-M-255 was identical to CTX-M-27 except for a G239S substitution. Here, we characterize the hydrolytic spectrum of CTX-M-255 and a previously reported β-lactamase, CTX-M-178, also containing a G239S substitution and compare it to their respective parental enzymes, CTX-M-27 and CTX-M-15. METHODS All β-lactamase genes were expressed in E. coli TOP10 and MICs to representative β-lactam-antibiotics were determined. Furthermore, blaCTX-M-15, blaCTX-M-27, blaCTX-M-178 and blaCTX-M-255 with C-terminal His-tag fusions were affinity purified for enzyme kinetic assays determining Michaelis-Menten kinetic parameters against representative β-lactam-antibiotics and IC50s of clavulanate, sulbactam, tazobactam and avibactam. RESULTS TOP10-transformants expressing blaCTX-M-178 and blaCTX-M-255 showed resistance to penicillin/β-lactamase combinations and susceptibility to cephalothin and cefotaxime in contrast to transformants expressing blaCTX-M-15 and blaCTX-M-27. Determination of enzyme kinetic parameters showed that CTX-M-178 and CTX-M-255 both lacked hydrolytic activity against cephalosporins and showed impaired hydrolytic efficiency against penicillin antibiotics compared to their parental enzymes. Both enzymes appeared more active against piperacillin compared to benzylpenicillin and ampicillin. Compared to their parental enzymes, IC50s of β-lactamase-inhibitors were increased more than 1000-fold for CTX-M-178 and CTX-M-255. CONCLUSIONS CTX-M-178 and CTX-M-255, both containing a G239S substitution, conferred resistance to piperacillin/tazobactam and may be characterized as inhibitor-resistant CTX-M β-lactamases. Inhibitor resistance was accompanied by loss of activity against cephalosporins and monobactams. These findings add to the necessary knowledge base for predicting antibiotic susceptibility from genotypic data.
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Affiliation(s)
- Minna Rud Andreasen
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
- Department of Clinical Microbiology, Copenhagen University Hospital-Amager and Hvidovre, Copenhagen, Denmark
| | - Tim Rick
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Nicolai Riff Alexandersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Katrine Hartung Hansen
- Department of Clinical Microbiology, Copenhagen University Hospital-Amager and Hvidovre, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Schou Pedersen
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jakob K Warweitzky
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Twincore, Centre for Experimental and Clinical Infection Research, A Joint Venture of the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Carolina Mastella Botelho
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Twincore, Centre for Experimental and Clinical Infection Research, A Joint Venture of the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Susanne Häussler
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department Molecular Bacteriology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Twincore, Centre for Experimental and Clinical Infection Research, A Joint Venture of the Helmholtz Centre for Infection Research and the Hannover Medical School, Hannover, Germany
| | - Lotte Jelsbak
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Kristian Schønning
- Department of Clinical Microbiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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