ABSTRACT
Although KPC enzymes are most common among carbapenemases produced by
Enterobacter cloacae
complex globally, the epidemiology varies from one country to another. While previous studies have suggested that IMP enzymes are most common in Japan, detailed analysis has been scarce thus far. Here, we carried out a molecular epidemiological study and plasmid analysis of IMP-1-producing
E. cloacae
complex isolates collected from three hospitals in central Tokyo using whole-genome sequencing. Seventy-one isolates were classified into several sequence types (STs), and 49 isolates were identified as
Enterobacter hormaechei
ST78. Isolates of ST78 were divided into three clades by core-genome single nucleotide polymorphism (SNP)-based phylogenetic analysis. Whereas isolates of clade 3 were isolated from only one hospital, isolates of clade 1 and 2 were identified from multiple hospitals. Ten of 12 clade 1 isolates and 1 of 4 clade 2 isolates carried
bla
IMP-1
on IncHI2 plasmids, with high similarity of genetic structures. In addition, these plasmids shared backbone structures with IncHI2 plasmids carrying
bla
IMP
reported from other countries of the Asia-Pacific region. All isolates of clade 3 except one carried
bla
IMP-1
in In1426 on IncW plasmids. An isolate of clade 3, which lacked IncW plasmids, carried
bla
IMP-1
in In1426 on an IncFIB plasmid. These observations suggest that IMP-producing
E. cloacae
complex isolates with a diversity of host genomic backgrounds have spread in central Tokyo, and they indicate the possible contribution of IncHI2 plasmids toward this phenomenon.
Characterization of a Clinical Enterobacter hormaechei Strain Belonging to Epidemic Clone ST418 Co-carrying blaNDM-1, blaIMP-4 and mcr-9.1