Origin of OXA-181, an emerging carbapenem-hydrolyzing oxacillinase, as a chromosomal gene in Shewanella xiamenensis.

Plasmid-mediated carbapenem-hydrolyzing β-lactamases are becoming emerging threats with Enterobacteriaceae. In particular, the carbapenem-hydrolyzing class D β-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-48)-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.