GES-66, Characterization of a new β-lactamase Gene Variant Detected in Klebsiella pneumoniae

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 supports GES-66 has carbapenemase activity.