The resistance of Enterobacteriaceae to colistin mediated by plasmid-borne mobile mcr genes is an emerging public health concern. This study aimed to explore the distribution and characteristics of Escherichia coli isolates harboring mcr genes from slaughtered pigs in Thailand from 2014 to 2015. A total of 779 E. coli isolates were assessed, of which 61 (7.8%) were found to carry mcr genes, including mcr-1, mcr-3, mcr-6, mcr-7, mcr-8, and mcr-9, together with co-occurrences of mcr-1+mcr-3, mcr-1+mcr-9, and mcr-3+mcr-6+mcr-7. In these mcr-harboring E. coli isolates, mcr-1 (40.9%) and mcr-9 (32.8%) were predominant. Colistin resistance was mainly mediated by the mcr-1 gene, whereas intermediate resistance was noted in isolates that harbored mcr-9, mcr-6, mcr-7, and mcr-8 genes. Most E. coli isolates harboring mcr genes were susceptible to third-generation cephalosporins and all of these isolates were susceptible to carbapenems. Clermont phylotyping demonstrated that mcr-harboring isolates mainly belonged to phylogroup A (44.3%), followed by phylogroups B1 (34.4%), D (14.8%), and B2 (6.6%). Multilocus sequence typing revealed that 25 sequence types (STs) were assigned to 45 mcr-harboring E. coli isolates, whereas the remaining 16 isolates were novel STs. The mcr-1 and mcr-9 genes were mostly predominant in ST101 and ST8900, respectively. This study provides a comprehensive insight into the prevalence and diversity of mcr-harboring E. coli isolates obtained from slaughtered pigs across Thailand. Strengthening of surveillance systems by the government for controlling and preventing mcr dissemination from animals to humans or vice versa is urgently needed. No clinical trial registration number.

中文翻译：

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泰国屠宰猪分离出的携带mcr基因的大肠杆菌的分布及分子特征

肠杆菌科细菌对由质粒携带的移动mcr基因介导的粘菌素的耐药性是一个新兴的公共卫生问题。本研究旨在探讨2014年至2015年泰国屠宰猪携带mcr基因的大肠杆菌分离株的分布和特征。共评估779株大肠杆菌，其中61株（7.8%）携带mcr基因，包括mcr-1、mcr-3、mcr-6、mcr-7、mcr-8和mcr-9，以及同时出现的mcr-1+mcr-3、mcr-1+mcr-9，和mcr-3+mcr-6+mcr-7。在这些携带mcr 的大肠杆菌分离株中，mcr-1 (40.9%) 和mcr-9 (32.8%) 占主导地位。粘菌素抗性主要由mcr-1基因介导，而在含有mcr-9、mcr-6、mcr-7和mcr-8基因的分离株中观察到中等抗性。大多数带有mcr基因的大肠杆菌分离株对第三代头孢菌素敏感，并且所有这些分离株都对碳青霉烯类敏感。克莱蒙系统发育证明mcr携带的分离株主要属于系统群 A (44.3%)，其次是系统群 B1 (34.4%)、D (14.8%) 和 B2 (6.6%)。多位点序列分型显示，25 种序列类型 (ST) 被分配给 45 个携带mcr 的大肠杆菌分离株，而其余 16 个分离株是新的 ST。的MCR-1和MCR-9基因大多主要在ST101和ST8900，分别。这项研究提供了对从泰国屠宰猪中获得的携带mcr 的大肠杆菌分离株的普遍性和多样性的全面了解。政府加强监控系统以控制和预防微污染迫切需要从动物传播给人类，反之亦然。无临床试验注册号。