Origin of OXA-181, an Emerging Carbapenem-Hydrolyzing Oxacillinase, as a Chromosomal Gene in Shewanella xiamenensis

Plasmid-mediated carbapenem-hydrolyzing beta-lactamases are becoming emerging threats with Enterobacteriaceae. In particular, the carbapenem-hydrolyzing class D beta-lactamase OXA-48 and its derivative OXA-181 have been reported increasingly worldwide. Using a PCR-based strategy, environmental samples were screened for bla(OXA-4)8-like genes. Shewanella xiamenensis, an environmental species from marine and freshwater, was identified as the progenitor of the bla(OXA-181) gene. This work identifies the reservoir of an emerging carbapenemase gene that is clinically significant.