摘要
      据报道，携带粘菌素抗性（mcr）-1的质粒在全球传播。本研究旨在使用全基因组测序来调查这些质粒的全球传播，以更 好地了解遗传特征。获得了67个含有mcr-1的完整质粒基因组。系统发育是针对完整的质粒基因组构建的。比较了不同复制子类型质粒的抗微生物耐药性基因（ARGs）、插入序列和其他功能基因。发现五种不同复制子类型的质粒（IncX4、IncI2、IncP1、IncHIA和IncFIB）携带mcr-1。IncX4和IncI2型质粒根据它们被分离的国家（而不是作为IncHIA和IncFIB）被很好地聚类。在mcr-1的上游和/或下游鉴定出三个插入序列（ISApl1、ISKpn26和IS1294）。在整个样品来源处观察到质粒IncX4和IncI2。质粒IncX4无论分离物的来源如何都表现出高度的一致性，并且携带H–NS编码基因，这是成功转移质粒的促进因素。在IncI2质粒中观察到所有三个插入序列。除了mcr-1外，IncHI2质粒还携带各种ARG。我们的结果阐明了携带质粒的完整mcr-1的特征和系统发育关系，表明mcr-1在全球的传播主要是由于质粒转移而不是克隆传播。
Abstract
Global dissemination of mobilized colistin resistance (mcr)-1-carrying plasmids has been reported. This study aimed to investigate the global dissemination of these plasmids using whole genome sequencing to provide better understanding on genetic characteristics. Sixty-seven complete plasmid genomes harboring mcr-1 were obtained. Phylogeny was built against full plasmid genomes. Different replicon types of plasmid were compared in terms of antimicrobial resistance genes (ARGs), insertion sequence, and other functional genes. Five different replicon types of plasmid (IncX4, IncI2, IncP1, IncHIA, and IncFIB) were found to harbor mcr-1. IncX4 and IncI2 types of plasmid were well clustered in accordance with the country where they were isolated (and not as IncHIA and IncFIB). Three insertion sequences (ISApl1, ISKpn26, and IS1294) were identified in up- and/or downstream of mcr-1. Plasmids IncX4 and IncI2 were observed across the sample origin. Plasmids IncX4 showed high uniformity regardless of the origin of isolates and harbored H–NS coding genes, a facilitator for successful plasmid transfer. All three insertion sequences were observed in IncI2 plasmids. IncHI2 plasmids harbored various ARGs in addition to mcr-1. Our results elucidate the characteristics and phylogenetic relationships of complete mcr-1-harboring plasmids, indicating that global dissemination of mcr-1 is primarily owing to plasmid transfer rather than clonal spread.

https://www.liebertpub.com/doi/full/10.1089/mdr.2021.0164