Anjum Muna F, Duggett Nicholas A, AbuOun Manal, Randall Luke, Nunez-Garcia Javier, Ellis Richard J, Rogers Jon, Horton Robert, Brena Camilla, Williamson Susanna, Martelli Francesca, Davies Robert, Teale Christopher
Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK.
J Antimicrob Chemother. 2016 Aug;71(8):2306-13. doi: 10.1093/jac/dkw149. Epub 2016 May 4.
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 β-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.
在从中国的大肠杆菌中鉴定出一种质粒介导的黏菌素耐药机制后，本研究旨在对从英国一个农场的猪身上分离出的耐黏菌素细菌进行特征描述。
采用肉汤稀释法进行表型抗菌药物敏感性测试，并进行全基因组测序（WGS）以检测编码耐药性和毒力的基因的存在。通过接合试验研究可转移的黏菌素耐药性。
两种大肠杆菌和一株鼠伤寒沙门氏菌哥本哈根变种被证明是多重耐药的，包括对黏菌素耐药，其中一株大肠杆菌和沙门氏菌携带mcr-1基因；所有三株菌在赋予黏菌素耐药性的基因中都存在染色体突变，并且两株大肠杆菌都具有β-内酰胺酶耐药性。沙门氏菌的mcr-1质粒与来自中国的pHNSHP45高度相似，而大肠杆菌的mcr-1质粒仅共有ISApII和mcr-1基因。沙门氏菌的mcr-1质粒通过接合转移到受体肠杆菌科细菌的频率很低，介于10^(-7)和10^(-9) 菌落形成单位/受体菌落形成单位之间。我们无法证明大肠杆菌的mcr-1质粒转移。质粒图谱分析表明沙门氏菌有多个质粒发生转移，产生了一些多重耐药的接合子。
在猪的肠杆菌科细菌中鉴定出mcr-1基因，证实了其在英国牲畜中的存在。结果表明耐药性通过不同的水平可转移元件进行传播。从沙门氏菌分离株体外转移携带黏菌素和其他耐药性的多个质粒，突显了更广泛传播和重组的可能性。
