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J Antimicrob Chemother. 2018 Jul 1;73(7):1791-1795. doi: 10.1093/jac/dky111.

Novel plasmid-mediated colistin resistance gene mcr-7.1 in Klebsiella pneumoniae.

Yang YQ1,2, Li YX1,2, Lei CW1,2, Zhang AY1,2, Wang HN1,2.

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Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Science, Sichuan University, Chengdu, China.
Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, Chengdu, China.



To identify a novel plasmid-mediated colistin resistance gene in Klebsiella pneumoniae isolated from chickens in China.


WGS was used to identify a novel colistin resistance gene. The transferability of plasmids carrying mcr-7.1 was investigated by conjugation experiments. The expression of the mcr-7.1 gene was examined using an expression vector.


A novel plasmid-mediated colistin resistance gene mcr-7.1, sharing 70% amino acid identity with the mcr-3 gene, was identified in three K. pneumoniae strains isolated from chickens in China. The mcr-7.1 gene was found in an IncI2-type plasmid (pSC20141012) that co-harboured the blaCTX-M-55 gene in one isolate. pSC20141012 can be transferred from K. pneumoniae SC20141012 to Escherichia coli J53Azr, exhibiting a ≥8-fold increase in colistin MIC compared with the recipient E. coli J53Azr.


We identified a novel plasmid-mediated colistin resistance gene named mcr-7.1 in K. pneumoniae in China. The prevalence of mcr-7.1 in various species of human and animal origin needs to be investigated immediately.

[Indexed for MEDLINE]

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