Molecular epidemiology of isolates with multiple mcr plasmids from a pig farm in Great Britain: the effects of colistin withdrawal in the short and long term
Molecular epidemiology of isolates with multiple mcr plasmids from a pig farm in Great Britain: the effects of colistin withdrawal in the short and long term
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DOI：
10.1093/jac/dky292
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发表时间：
2018-11-01
影响因子：
5.2
通讯作者：
Anjum, Muna F.
中科院分区：
文献类型：
--
作者：
Duggett, Nicholas A.;Randall, Luke P.;Anjum, Muna F.
背景资料：包括农场在内的环境可能成为移动的粘菌素耐药性（mcr）基因的储存库，这导致人们呼吁减少在牲畜中使用粘菌素，这是人类的最后一种抗生素。目标：为了从两组猪的粪便中确定mcr肠杆菌科的分子流行病学，其中一组最初接受粘菌素给药，另一组未接受，方法：从阳性粪便中分离出mcr-1肠杆菌科细菌，进行WGS，对选定的大肠杆菌进行接合，测定其最低抑菌浓度（MIC）。在5个月内从两个队列中分离出携带mcr-1和多种耐药基因的不同ST的大肠杆菌。来自给药队列的2例ST同时含有mcr-1和mcr-3质粒，一些分离株还在不同质粒上携带多个mcr-1拷贝。mcr-1质粒分为4种Inc型（X4、pO 111、I2和HI 2），其中mcr-3见于IncP。多拷贝mcr质粒对粘菌素MIC无明显影响，但它们可在体外同时转移至沙门氏菌宿主。无论是mcr-1，也没有mcr-3中检测到的样本收集到类似的20个月后，粘菌素sustain.Conclusions：我们报告的第一个已知的时间在英国的mcr-3的MDR肠杆菌科，这可能同时窝藏多个拷贝的mcr-1不同的质粒上的存在。然而，控制措施，包括停止粘菌素，可以成功地减轻长期的农场持久性。
Background: The environment, including farms, might act as a reservoir for mobile colistin resistance (mcr) genes, which has led to calls for reduction of usage in livestock of colistin, an antibiotic of last resort for humans.Objectives: To establish the molecular epidemiology of mcr Enterobacteriaceae from faeces of two cohorts of pigs, where one group had initially been treated with colistin and the other not, over a 5 month period following stoppage of colistin usage on a farm in Great Britain; faecal samples were also taken at similar to 20 months.Methods: mcr-1 Enterobacteriaceae were isolated from positive faeces and was WGS performed; conjugation was performed on selected Escherichia coli and colistin MICs were determined.Results: E. coli of diverse ST harbouring mcr-1 and multiple resistance genes were isolated over 5 months from both cohorts. Two STs, from treated cohorts, contained both mcr-1 and mcr-3 plasmids, with some isolates also harbouring multiple copies of mcr-1 on different plasmids. The mcr-1 plasmids grouped into four Inc types (X4, pO111, I2 and HI2), with mcr-3 found in IncP. Multiple copies of mcr plasmids did not have a noticeable effect on colistin MIC, but they could be transferred simultaneously to a Salmonella host in vitro. Neither mcr-1 nor mcr-3 was detected in samples collected similar to 20 months after colistin cessation.Conclusions: We report for the first known time on the presence in Great Britain of mcr-3 from MDR Enterobacteriaceae, which might concurrently harbour multiple copies of mcr-1 on different plasmids. However, control measures, including stoppage of colistin, can successfully mitigate long-term on-farm persistence.