Diversified mcr-1-Harbouring Plasmid Reservoirs Confer Resistance to Colistin in Human Gut Microbiota.

Huiyan Ye,Zhencui Li,Youjun Feng,Ronghui Wen,Han Zhang,George F Gao,Rongsui Gao,Qinghua Hu,Yihui Li,Karen Bush

doi:10.1128/mbio.00177-16

Abstract

ABSTRACTColistin is an ultimate line of refuge against multidrug-resistant Gram-negative pathogens. Very recently, the emergence of plasmid-mediated mcr-1 colistin resistance has become a great challenge to global public health, raising the possibility that dissemination of the mcr-1 gene is underestimated and diversified. Here, we report three cases of plasmid-carried MCR-1 colistin resistance in isolates from gut microbiota of diarrhea patients. Structural and functional analyses determined that the colistin resistance is conferred purely by the single mcr-1 gene. Genetic and sequence mapping revealed that mcr-1-harbouring plasmid reservoirs are present in diversity. Together, the data represent the first evidence of diversity in mcr-1-harbouring plasmid reservoirs of human gut microbiota.

Highlights

Colistin is an ultimate line of refuge against multidrug-resistant Gram-negative pathogens
Given the fact that current knowledge on the genetic evolution of both the mcr-1 gene and the mcr-1harbouring vectors and plasmids is extremely limited, we anticipated that genetic diversity of mcr-1carrying plasmid backbones/reservoirs is probably present in gut microbiota of animals as well as human beings
Following routine examination procedures such as 16S sequencing, we investigated 48 isolates of Escherichia coli and 27 isolates of K. pneumoniae

Summary

Introduction

Colistin is an ultimate line of refuge against multidrug-resistant Gram-negative pathogens. We report three cases of plasmid-carried MCR-1 colistin resistance in isolates from gut microbiota of diarrhea patients and functionally define the colistin resistance conferred purely by the single mcr-1 gene. Liu et al (5) reported, for the first time, that plasmid-mediated mcr-1 colistin resistance in animal and human isolates of Escherichia coli and Klebsiella pneumoniae has emerged in China (Fig. 1 and 2). They defined an unusual mechanism for colistin resistance in that the mcr-1 gene product belongs to the family of phosphoethanolamine transferase enzymes (Fig. 2b) (5). It is very true that plasmid pHNSHP45 from the Chinese swine microbiota (Fig. 2a) is the only one (among hundreds of examples of mcr-1 carriage in animal/human isolates) with the known full genome sequence in China (5)

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Results

Conclusion