Kun Ye, Yongqing Zhang, Xuemei Qiu, Liyan Ye, Jiyong Yang, Yanning Ma
The carbapenem-resistant Enterobacter cloacae (CREC) have become a global health concern. However, our understanding of its epidemiological trends and resistance mechanisms still needs to be improved. Ninety-one non-repetitive clinical CREC isolates were collected from 12 hospitals across China and identified using MALDI-TOF MS, rMLST, ANI, MASH, and dDDH. Minimal inhibitory concentrations were determined via broth microdilution. Resistance genes and plasmid replicons were identified using ResFinder and PlasmidFinder. Carbonyl cyanide 3-chlorophenylhydrazone suppression test and OmpC and OmpF overexpression test were conducted on 32 non-carbapenemase-producing (NCP) isolates. A phylogenetic tree was constructed with kSNP4 and visualized through iTOL. Among the 91 CREC isolates, E. hormaechei was predominate (75 isolates), followed by E. kobei (five isolates). Within E. hormaechei , E. hormaechei subsp xiangfangensis was the most widespread subspecies. Sixty isolates produced carbapenemase, with bla NDM-1 identified in 36 isolates, bla KPC-2 in six isolates , and bla NDM-5 in six isolates. Two isolates harbored both bla NDM-1 and bla KPC-2 . Thirty-two isolates were NCP isolates, primarily due to carbonyl cyanide 3-chlorophenylhydrazone suppression. Among CREC in China, the bla NDM-1 was the dominant carbapenemase-coding gene. For NCP isolates, efflux pumps were the main reason for carbapenem resistance, and susceptibility could be restored in an antibiotic-free environment.