Table_1_Emergence of blaNDM–1-carrying Enterobacter chengduensis in China.XLSX

IntroductionEnterobacter chengduensis was defined as a novel species in the genus. Enterobacter in 2019, however, antimicrobial resistance, such as carbapenem resistance, has rarely been described in E. chengduensis. This study described the molecular features of four carbapenem-resistant E. chengduensis strains collected from a tertiary health care hospital in Southwest China.
MethodsWhole genome sequencing (WGS) was used to determine the genome sequence of four E. chengduensis strains. The precise species of strains were identified by average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH). The clonal relatedness of four E. chengduensis strains and additional 15 ones from NCBI were examined through phylogenetic analysis. The molecular features of E. chengduensis and genetic structure of carbapenemase- encoding plasmids were characterized through genomic annotation and analysis.
ResultsThe results revealed the emergence of blaNDM–1-carrying E. chengduensis strains in China. Multilocus sequence typing (MLST) analysis showed that all 19 E. chengduensis belonged to the same sequence type of ST414. Core SNP analysis suggested the potential intrahospital clonal transmission of ST414 E. chengduensis. The carbapenemase-encoding gene blaNDM–1 was harbored by an IncC-type plasmid, which was experimentally confirmed to be able to conjugate.
DiscussionThis study reports the first emergence and potential clonal transmission of blaNDM–1-carrying E. chengduensis. Further surveillance should be advocated to monitor the dissemination of carbapenem-resistant E. chengduensis and blaNDM–1-harboring IncC-type plasmids in China.

引言
成都肠杆菌 (Enterobacter chengduensis) 于2019年被正式定为肠杆菌属 (Enterobacter) 的一个新种，但目前关于该菌的抗菌药物耐药性（如碳青霉烯类耐药性）的相关报道仍较为罕见。本研究对中国西南地区某三级医院分离得到的4株碳青霉烯类耐药成都肠杆菌的分子特征进行了分析。
方法
采用全基因组测序 (Whole genome sequencing, WGS) 对4株成都肠杆菌的基因组序列进行测定。通过平均核苷酸同源性 (average nucleotide identity, ANI) 与计算机模拟DNA-DNA杂交 (in silico DNA-DNA hybridization, isDDH) 对菌株进行精准物种鉴定。利用系统发育分析，对本研究中的4株成都肠杆菌及NCBI数据库中额外的15株成都肠杆菌的克隆相关性进行考察。通过基因组注释与分析，对成都肠杆菌的分子特征及碳青霉烯酶编码质粒的遗传结构进行解析。
结果
本研究证实中国境内出现了携带blaNDM–1基因的成都肠杆菌菌株。多位点序列分型 (multilocus sequence typing, MLST) 分析显示，全部19株成都肠杆菌均属于序列型ST414。核心单核苷酸多态性分析结果提示，ST414型成都肠杆菌可能存在医院内克隆传播现象。携带碳青霉烯酶编码基因blaNDM–1的质粒为IncC型质粒，实验验证该质粒可发生接合转移。
讨论
本研究首次报道了携带blaNDM–1基因的成都肠杆菌的出现及其潜在的克隆传播风险。建议进一步加强监测工作，以监控中国境内碳青霉烯类耐药成都肠杆菌及携带blaNDM–1的IncC型质粒的传播扩散情况。