Mobile colistin resistance (mcr) genes represent an emerging challenge. Here we describe a novel mcr gene, mcr-10, on an IncFIA plasmid of an Enterobacter roggenkampii clinical strain. mcr-10 has the highest nucleotide identity (79.69%) with mcr-9 and encodes MCR-10 with 82.93% amino acids identical to MCR-9. mcr-10 confers 4-fold increase in colistin MIC (from 1 to 4 mg/L) when cloned into a colistin-susceptible E. roggenkampii strain. By screening GenBank, mcr-10 was found in various Enterobacteriaceae species of countries in four continents, suggesting that this gene has widely spread. MCR-10 shows 79.04% to 83.67% amino acid identity and highly conserved predicted protein structures with chromosomally encoded MCR-like phosphoethanolamine transferases (designated MCR-B here) of various Buttiauxella species. MCR-10, MCR-9 and MCR-B proteins may, therefore, originate from a common ancestor. mcr-10 was adjacent to a site-specific recombinase-encoding gene and was bracketed by IS903 and may be mobilized by site-specific recombination or composite transposon. Our results indicate that mcr-10 is a novel plasmid-borne colistin resistance gene and warrants immediate monitoring and further studies.

中文翻译：

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新的可移动大肠粘菌素抗性基因mcr-10的鉴定。

可移动的粘菌素抗性（mcr）基因代表了一个新兴的挑战。在这里，我们描述了罗氏肠杆菌临床菌株的IncFIA质粒上的新型mcr基因mcr-10。mcr-10与mcr-9具有最高的核苷酸同一性（79.69％），并编码具有与MCR-9相同的82.93％氨基酸的MCR-10。当将mcr-10克隆到对大肠埃希氏菌敏感的罗氏大肠杆菌中时，其大肠埃希氏菌MIC增加4倍（从1到4 mg / L）。通过筛选GenBank，在四大洲的各个国家的肠杆菌科物种中发现了mcr-10，表明该基因已广泛传播。MCR-10表现出79.04％到83.67％的氨基酸同一性，并且具有各种Buttiauxella物种的染色体编码的MCR样磷酸乙醇胺转移酶（此处称为MCR-B）的高度保守的预测蛋白质结构。MCR-10，MCR-9和MCR-B蛋白可能 因此，起源于一个共同的祖先。mcr-10与位点特异性重组酶编码基因相邻，被IS903括起来，可以通过位点特异性重组或复合转座子动员。我们的结果表明，mcr-10是一种新型的质粒携带的大肠粘菌素抗性基因，值得立即监测和进一步研究。