The development of colistin resistance in carbapenem-resistant strains poses a serious public health problem. In this study, we collected 249 carbapenem-resistant Escherichia coli isolates from patients in Seoul in 2018, and screened all isolates for colistin resistance and for the presence of mobile colistin resistance (mcr) genes. Colistin-resistant strains were further analyzed using multilocus sequence typing, antimicrobial susceptibility testing, detection of antibiotic resistance determinants, plasmid transconjugation, and whole-genome sequencing. Three of the 249 carbapenem-resistant isolates were resistant to colistin, and mcr-1 was detected in one isolate (SECR18-0888), which belonged to sequence type 156 and was resistant to all antibiotics tested except tigecycline. The mcr-1.1 gene was located on an ~62 kb self-transferable IncI2 plasmid along with the bla_CTX-M-55 gene, and the bla_NDM-1, bla_TEM, qepA1, and rmtB genes were additionally detected in SECR18-0888. As an extensively drug-resistant E. coli strain producing MCR-1 and NDM-1 was identified in Korea for the first time, continued monitoring of colistin resistance in carbapenem-resistant Enterobacteriaceae should be reinforced.

碳青霉烯类耐药菌株中粘菌素耐药性的发展构成了严重的公共卫生问题。在这项研究中，我们于 2018 年从首尔的患者中收集了 249 株耐碳青霉烯类大肠埃希菌，并筛选了所有分离株的粘菌素耐药性和移动粘菌素耐药性 ( mcr ) 基因的存在。使用多位点序列分型、抗菌药敏试验、抗生素耐药决定因素检测、质粒转导和全基因组测序进一步分析了粘菌素耐药菌株。249 株碳青霉烯类耐药菌株中有 3 株对粘菌素和mcr-1耐药。在一个分离株（SECR18-0888）中检测到，该分离株属于序列类型 156，对除替加环素外的所有测试抗生素均耐药。mcr-1.1基因与bla _CTX-M-55基因一起位于约 62 kb 可自我转移的 IncI2 质粒上，并且在 SECR18-0888中额外检测到bla _NDM-1、bla _TEM、qepA1和rmtB基因. 由于在韩国首次鉴定出产生 MCR-1 和 NDM-1的广泛耐药大肠杆菌菌株，因此应加强对耐碳青霉烯类肠杆菌科粘菌素耐药性的持续监测。