CMY-1/MOX-family AmpC beta-lactamases MOX-1, MOX-2 and MOX-9 were mobilized independently from three Aeromonas species

Objectives: To investigate the origin of CMY-1/MOX-family beta-lactamases. Methods: Publicly available genome assemblies were screened for CMY-1/MOX genes. The loci of CMY-1/MOX genes were compared with respect to synteny and nucleotide identity, and subjected to phylogenetic analysis. Results: The chromosomal ampC genes of several Aeromonas species were highly similar to known mobile CMY-1/MOX variants. Annotation and sequence comparison revealed nucleotide identities >98% and conserved syntenies between MOX-1-, MOX-2- and MOX-9-associated mobile sequences and the chromosomal Aeromonas sanarellii, Aeromonas caviae and Aeromonas media ampC loci. Furthermore, the phylogenetic analysis showed that MOX-1, MOX-2 and MOX-9 formed three distinct monophyletic groups with the chromosomal ampC genes of A. sanarellii, A. caviae and A. media, respectively. Conclusions: Our findings show that three CMY-1/MOX-family beta-lactamases were mobilized independently from three Aeromonas species and hence shine new light on the evolution and emergence of mobile antibiotic resistance genes.