摘要

已显示肠杆菌科（包括大肠杆菌）获得粘菌素抗性基因mcr-1。 2016年从中国上海的奶牛粪便中分离出一种大肠杆菌菌株EC11，该菌株对粘菌素，多粘菌素B和甲氧苄氨嘧啶 - 磺胺甲恶唑具有抗性。菌株EC11鉴定为序列型ST278，并且易受19种常用抗生素的影响。菌株EC11的全基因组测序显示该菌株含有31kb抗性质粒pEC11b，其属于IncX4组。显示mcr-1基因插入pEC11b的2.6-kb mcr-1-pap2盒中。质粒pEC11b还含有推定的结合转移组分，包括oriT样区，松弛酶，IV型偶联蛋白和IV型分泌系统。我们成功地将pEC11b转移到大肠杆菌C600中，平均转接效率为4.6×10-5。此外，基于MLST的分析比较EC11和其他报道的mcr阳性大肠杆菌群体显示出高基因型多样性。在上海发现了对粘菌素具有抗性的大肠杆菌菌株EC11，强调了警惕在检测mcr基因等新威胁对公众健康的重要性。检测mcr基因有助于跟踪，减缓和应对中国畜牧业抗生素耐药性的出现。

Enterobacteriaceae, including Escherichia coli, has been shown to acquire the colistin resistance gene mcr-1. A strain of E. coli, EC11, which is resistant to colistin, polymyxin B and trimethoprim-sulfamethoxazole, was isolated in 2016 from the feces of a dairy cow in Shanghai, China. Strain EC11 identifies with sequence type ST278 and is susceptible to 19 frequently used antibiotics. Whole genome sequencing of strain EC11 showed that this strain contains a 31-kb resistance plasmid, pEC11b, which belongs to the IncX4 group. The mcr-1 gene was shown to be inserted into a 2.6-kb mcr-1-pap2 cassette of pEC11b. Plasmid pEC11b also contained putative conjugal transfer components, including an oriT-like region, relaxase, type IV coupling protein, and type IV secretion system. We were successful in transferring pEC11b to E. coli C600 with an average transconjugation efficiency of 4.6 × 10-5. Additionally, a MLST-based analysis comparing EC11 and other reported mcr-positive E. coli populations showed high genotypic diversity. The discovery of the E. coli strain EC11 with resistance to colistin in Shanghai emphasizes the importance of vigilance in detecting new threats like mcr genes to public health. Detection of mcr genes helps in tracking, slowing, and responding to the emergence of antibiotic resistance in Chinese livestock farming.

https://www.ncbi.nlm.nih.gov/pubmed/30559724