Epidemiological characteristics and molecular features of carbapenem-resistant Enterobacter strains in China: A multicenter genomic study.

Epidemiological characteristics and molecular features of carbapenem-resistant Enterobacter (CR- Ent ) species remain unclear in China. In this study, we performed a genomic study on 92 isolates from Enterobacter -caused infections from a multicenter study in China. Whole genome sequencing (WGS) was used to determine the genome sequence of 92 non-duplicated CR- Ent strains collected from multiple tertiary health centers. The precise species of Enterobacter strains were identified by average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH). Molecular features of high-risk CR- Ent sequence type (ST) lineages and carbapenemase-encoding plasmids were determined. The result revealed that the most common human-source CR- Ent species in China was E. xiangfangensis (66/92, 71.93%), and the proportion of carbapenemase-producing Enterobacter (CP- Ent ) in CR- Ent was high (72/92, 78.26%) in comparison to other global regions. Furthermore, ST171 and ST116 E. xiangfangensis were the major lineages of CP- Ent strains, and ST171 E. xiangfangensis was more likely to cause infections in older patients. Genomic analysis also highlighted the likelihood of intra-hospital/inter-hospital clonal transmission of ST171 and ST116 E. xiangfangensis . In addition, the bla NDM -harboring IncX3-type plasmid was identified as the prevalent carbapenemase-encoding plasmid carried by CR- Ent strains, and was experimentally confirmed to be able to self-transfer with high frequency. This study detailed the genomic and clinical characteristics of CR- Ent in China in the form of multicenter for the first time. The high risk of carbapenemase-producing ST171 and ST116 E. xiangfangensis , and the bla NDM -harboring IncX3-type plasmid were detected and emphasized.