Research Papers: Immunology:
Complex dissemination of the diversified mcr-1-harbouring plasmids in Escherichia coli of different sequence types
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Qingjing Wang1,*, Zhencui Li1,*, Jingxia Lin1, Xiuna Wang1,3, Xianbo Deng2 and Youjun Feng1
1 Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
2 College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
3 Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
* The authors have contributed equally to this work
Youjun Feng, email:
Xianbo Deng, email:
Keywords: MCR-1, diversity, sequence type (ST), Immunology and Microbiology Section, Immune response, Immunity
Received: August 23, 2016 Accepted: October 07, 2016 Published: October 12, 2016
The emergence of the mobilized colistin resistance gene, representing a novel mechanism for bacterial drug resistance, challenges the last resort against the severe infections by Gram-negative bacteria with multi-drug resistances. Very recently, we showed the diversity in the mcr-1-carrying plasmid reservoirs from the gut microbiota. Here, we reported that a similar but more complex scenario is present in the healthy swine populations, Southern China, 2016. Amongst the 1026 pieces of Escherichia coli isolates from 3 different pig farms, 302 E. coli isolates were determined to be positive for the mcr-1 gene (30%, 302/1026). Multi-locus sequence typing assigned no less than 11 kinds of sequence types including one novel Sequence Type to these mcr-1-positive strains. PCR analyses combined with the direct DNA sequencing revealed unexpected complexity of the mcr-1-harbouring plasmids whose backbones are at least grouped into 6 types four of which are new. Transcriptional analyses showed that the mcr-1 promoter of different origins exhibits similar activity. It seems likely that complex dissemination of the diversified mcr-1-bearing plasmids occurs amongst the various ST E. coli inhabiting the healthy swine populations, in Southern China.
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