Mobile class A ß-lactamase gene bla GMA-1.

IMPORTANCE: Despite increasing reports, class A ß-lactamases of environmental bacteria remain very poorly characterized, with limited understanding of their transmission patterns. To address this knowledge gap, we focused on a recently designated GMA family ß-lactamase gene, bla GMA-1, found in marine bacterial genera such as Vibrio. This study shows that gammaproteobacterial mobile class A ß-lactamase is specialized for penicillin degradation, and bla GMA-1 is frequently linked to strand-biased circularizing integrative elements (SEs) in sequences in the RefSeq/GenBank database. Evidence for the implication of SEs in ß-lactamase environmental transmission provides insights for future surveillance studies of antimicrobial resistance genes in human clinical settings.