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. 2025 Nov 14;232(5):1139-1143.
doi: 10.1093/infdis/jiaf302.

GES-66: Characterization of a New β-Lactamase Gene Variant Detected in Klebsiella pneumoniae

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GES-66: Characterization of a New β-Lactamase Gene Variant Detected in Klebsiella pneumoniae

Florencia Martino et al. J Infect Dis. .

Abstract

Guiana extended-spectrum (GES) β-lactamase enzymes have been traditionally classified as extended-spectrum β-lactamases; however, there are increasing reports of GES variants with carbapenemase activity. This study reports the first characterization of GES-66, a GES type not previously described, detected in a pair of sequence type 252 Klebsiella pneumoniae isolates from clinical and environmental sources in Argentina. GES-66 differs from GES-5 by a single amino acid substitution, E104K, while retaining the G170S alteration. Our data support that GES-66 has carbapenemase activity.

Keywords: Klebsiella pneumoniae; GES; GES-66; plasmid-mediated resistance; β-lactamase.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

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