Colistin resistance in Salmonella and Escherichia coli isolates from a pig farm in Great Britain
Colistin resistance in Salmonella and Escherichia coli isolates from a pig farm in Great Britain
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DOI：
10.1093/jac/dkw149
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发表时间：
2016-08-01
影响因子：
5.2
通讯作者：
Teale, Christopher
中科院分区：
文献类型：
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作者：
Anjum, Muna F.;Duggett, Nicholas A.;Teale, Christopher
本研究的目的是从英国某养猪场分离的粘菌素耐药细菌中鉴定出一种来自中国的大肠杆菌的质粒型粘菌素耐药机制。用肉汤稀释法进行表型药敏试验，并用WGS检测编码抗菌素和毒力的基因的存在。2株大肠埃希菌和1株鼠伤寒沙门氏菌哥本哈根分离株均为多药耐药，其中1株大肠埃希菌和1株沙门氏菌携带mcr-1基因；3株大肠埃希菌均存在粘菌素抗性基因的染色体突变，两株大肠埃希菌均对β-内酰胺酶耐药。沙门氏菌mcr-1与来自中国的pHNSHP45高度相似，而大肠杆菌mcr-1只有ISApII和mcr-1基因。沙门氏菌mcr-1通过接合转移到受体肠杆菌的频率很低，在10(-7)~10(-9)cfu/受体CFU之间。我们无法证明mcr-1质粒从大肠杆菌中转移。质粒谱分析表明沙门氏菌的多个质粒转移导致了一些多药耐药转移。在猪肠杆菌科中鉴定mcr-1基因证实了它在英国家畜中的存在。结果表明，抗性通过不同的水平可转移因子传播。从沙门氏菌分离株中携带粘菌素和其他耐药性的多个质粒的体外转移突显了更广泛传播和重组的可能性。
The objective of this study was to characterize colistin-resistant bacteria isolated from pigs on a farm in Great Britain following identification of a plasmid-borne colistin resistance mechanism in Escherichia coli from China.Phenotypic antimicrobial susceptibility testing was undertaken by broth dilution and WGS was performed to detect the presence of genes encoding resistance and virulence. Transferable colistin resistance was investigated by conjugation.Two E. coli and one Salmonella Typhimurium variant Copenhagen were shown to be MDR, including resistance to colistin, with one E. coli and the Salmonella carrying the mcr-1 gene; all three harboured chromosomal mutations in genes conferring colistin resistance and both E. coli harboured beta-lactamase resistance. The Salmonella mcr-1 plasmid was highly similar to pHNSHP45, from China, while the E. coli mcr-1 plasmid only had the ISApII and mcr-1 genes in common. The frequency of mcr-1 plasmid transfer by conjugation to recipient Enterobacteriaceae from Salmonella was low, lying between 10(-7) and 10(-9) cfu/recipient cfu. We were unable to demonstrate mcr-1 plasmid transfer from the E. coli. Plasmid profiling indicated transfer of multiple plasmids from the Salmonella resulting in some MDR transconjugants.Identification of the mcr-1 gene in Enterobacteriaceae from pigs confirms its presence in livestock in Great Britain. The results suggest dissemination of resistance through different horizontally transferable elements. The in vitro transfer of multiple plasmids carrying colistin and other resistances from the Salmonella isolate underlines the potential for wider dissemination and recombination.