Prevalence and Molecular Characterization of mcr-1-Positive Salmonella Strains Recovered from Clinical Specimens in China
Prevalence and Molecular Characterization of mcr-1-Positive Salmonella Strains Recovered from Clinical Specimens in China
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DOI：
10.1128/aac.02471-16
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发表时间：
2017-05-01
影响因子：
4.9
通讯作者：
Chen, Sheng
中科院分区：
文献类型：
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作者：
Cui, Mingquan;Zhang, Jinfei;Chen, Sheng
最近发现的粘菌素耐药元件mcr-1，增加了抗菌素耐药基因的名单，这些耐药基因不仅迅速削弱了常用抗生素的抗菌效力，而且也削弱了碳青霉烯类和粘菌素的最后一线药物的抗菌效力。本研究调查了从中国临床环境中回收的沙门氏菌菌株中移动的粘菌素耐药决定簇mcr-1的流行率，以及此类分离株携带的携带mcr-1的移动的元件的传播潜力。在1.4%的检测临床分离株中可回收mcr-1基因，其中大多数属于肠道沙门氏菌鼠伤寒血清型。这些菌株表现出不同的脉冲场凝胶电泳（PFGE）的配置文件和高耐药性的抗生素以外的粘菌素，特别是头孢菌素。质粒分析显示，mcr-1携带在大小范围从近似30 kb到近似250 kb的各种质粒上，其中有近似30 kb、近似60 kb和近似250 kb的接合性质粒，以及近似140 kb、近似180 kb和近似240 kb的非接合性质粒。代表性mcr-1携带质粒的测序显示，所有接合质粒均属于IncX 4、Incl 2和IncHl 2类型，与先前报告的相应类型质粒高度相似。非接合性质粒均属于IncH 12型，这些质粒的不可转移性归因于携带部分或全部tra基因的区域的丢失。我们的数据显示，与大肠埃希菌中的情况相似，沙门氏菌中mcr-1的传播被各种质粒加速，这表明携带mcr-1的质粒在肠杆菌科不同种属之间的传播可能是一种常见事件。
The recently discovered colistin resistance element, mcr-1, adds to the list of antimicrobial resistance genes that rapidly erode the antimicrobial efficacy of not only the commonly used antibiotics but also the last-line agents of carbapenems and colistin. This study investigated the prevalence of the mobile colistin resistance determinant mcr-1 in Salmonella strains recovered from clinical settings in China and the transmission potential of mcr-1-bearing mobile elements harbored by such isolates. The mcr-1 gene was recoverable in 1.4% of clinical isolates tested, with the majority of them belonging to Salmonella enterica serotype Typhimurium. These isolates exhibited diverse pulsed-field gel electrophoresis (PFGE) profiles and high resistance to antibiotics other than colistin and particularly to cephalosporins. Plasmid analysis showed that mcr-1 was carried on a variety of plasmids with sizes ranging from similar to 30 to similar to 250 kb, among which there were conjugative plasmids of similar to 30 kb, similar to 60 kb, and similar to 250 kb and nonconjugative plasmids of similar to 140 kb, similar to 180 kb, and similar to 240 kb. Sequencing of representative mcr-1-carrying plasmids revealed that all conjugative plasmids belonged to the IncX4, Incl2, and IncHl2 types and were highly similar to the corresponding types of plasmids reported previously. Nonconjugative plasmids all belonged to the IncHl2 type, and the nontransferability of these plasmids was attributed to the loss of a region carrying partial or complete tra genes. Our data revealed that, similar to the situation in Escherichia coli, mcr-1 transmission in Salmonella was accelerated by various plasmids, suggesting that transmission of mcr-1-carrying plasmids between different species of Enterobacteriaceae may be a common event.