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

Martino, Florencia; De Belder, Denise; Rapoport, Melina; Monge, Renata; Forastiero, Agustina; Moser, Kara A; Fabre, Valeria; Corso, Alejandra et al. · J Infect Dis · 2025

basic_science · Level V

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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.

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