Occurrence of Enterobacter hormaechei carrying bla_NDM-1 and bla_KPC-2 in China

Three carbapenem-resistant clinical isolates of the Enterobacter cloacae complex (ECC) were recovered from different patients in a hospital. All 3 isolates carried 2 carbapenemase genes bla_KPC-2 and bla_NDM-1. A study was performed to characterize their relatedness and to investigate possible links among the patients. Whole genome sequencing revealed that the isolates were Enterobacter hormaechei and belonged to ST177 of the ECC. There were 19-142 single nucleotide polymorphisms (SNPs) between the isolates, suggesting that the isolates were likely from a central reservoir, which might have existed for some time. bla_KPC-2 and bla_NDM-1 were carried on 2 different IncF-type plasmids in the isolates. The 3 bla_NDM-1-carrying plasmids were almost identical and were self-transmissible, while the bla_KPC-2-carrying plasmids were only transmissible in the presence of the bla_NDM-1-carrying plasmid. The source of and direct links among them were not identified, suggesting a hospital transmission of a common multidrug resistant strain.