Isolation of an IncP-1 plasmid harbouring mcr-1 from a chicken isolate of Citrobacter braakii in China
Isolation of an IncP-1 plasmid harbouring mcr-1 from a chicken isolate of Citrobacter braakii in China
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从中国布氏柠檬酸杆菌鸡分离株中分离携带 mcr-1 的 IncP-1 质粒
DOI：
10.1016/j.ijantimicag.2017.12.030
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发表时间：
2018-06-01
影响因子：
10.8
通讯作者：
Zhang, Anyun
中科院分区：
文献类型：
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作者：
Liu, Jinxin;Yang, Yanxian;Zhang, Anyun
质粒介导的粘菌素抗性基因 mcr-1 已在世界各地被发现，但携带该基因的生物体的多样性尚不清楚。在这项研究中，12 种耐粘菌素柠檬酸杆菌属。从中国的病鸡或死鸡中获得分离株，PCR 分析表明其中 5 只呈 mcr-1 阳性。选择一种具有多重耐药表型的布氏柠檬酸杆菌菌株（SCC4）进行进一步分析。 SCC4对10种受试抗生素呈耐药或中度耐药，粘菌素最低抑菌浓度(MIC)>4μg/mL。接合试验证明粘菌素抗性成功转移至大肠杆菌菌株 J53，频率为每个受体细胞 10(-7) 个细胞。全基因组测序显示，SCC4的基因组中含有13个抗生素抗性基因，mcr-1基因位于最近发现的IncP-1进化枝的44 kb自传IncP型质粒上。此外，mcr-1基因是插入元件(ISApl1-mcr-1-orf-ISApl1)的一部分，其以环状中间形式从质粒中切除。这是动物源性 mcr-1 阳性布氏棒状杆菌的首次报道，这些发现强调了这样一个事实：mcr-1 基因可以作为广泛宿主范围质粒的一部分存在于正常肠道菌群中。 (c) 2017 年 Elsevier B.V. 和国际化疗协会。版权所有。
The plasmid-mediated colistin resistance gene mcr-1 has been found worldwide, but the diversity of organisms harbouring this gene is unknown. In this study, 12 colistin-resistant Citrobacter spp. isolates were obtained from diseased or dead chickens in China, and PCR analysis indicated that five were positive for mcr-1. One Citrobacter braakii strain (SCC4) with a multidrug-resistant phenotype was chosen for further analysis. SCC4 was resistant or intermediate-resistant to ten of the tested antibiotics, and the colistin minimum inhibitory concentration (MIC) was >4 mu g/mL. A conjugation assay demonstrated successful transfer of colistin resistance to Escherichia coli strain J53 at a frequency of 10(-7) cells per recipient cell. Whole-genome sequencing revealed that SCC4 contained 13 antibiotic resistance genes in its genome, and the mcr-1 gene resided on a 44-kb self-transmissible IncP-type plasmid of a recently discovered IncP-1 clade. In addition, the mcr-1 gene was part of an insertion element (ISApl1-mcr-1-orf-ISApl1) that was excised from the plasmid as a circular intermediate form. This is the first report of mcr-1-posiitve C. braakii of animal origin and these findings highlight the fact that the mcr-1 gene can be found in normal enteric flora as part of broad-host-range plasmids. (c) 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.