Emergence of Raoultella ornithinolytica Coproducing IMP-4 and KPC-2 Carbapenemases in China

We report here the emergence of seven IMP-4-producing Raoultella ornithinolytica isolates obtained from one patient. All isolates carried the bla(IMP-4) carbapenemase gene, five isolates also carried bla(SHV-12), four contained bla(TEM-1), and one contained bla(OXA-1). Notably, the R. ornithinolytica isolate Ro25724 also expressed Klebsiella pneumoniae carbapenemase (KPC)-2. The bla(KPC-2) gene was located on a Tn3-Tn4401 integration structure on a plasmid of similar to 450 kb. This is the first description of the coexistence of bla(KPC-2) and bla(IMP-4) from the genus Raoultella.