Colistin Resistance Gene <i>mcr-1</i> and Its Variant in Escherichia coli Isolates from Chickens in China

Abstract

The <i>mcr-1</i> gene was detected in 5.11% (58/1136) of <i>Escherichia coli</i> isolates of chicken origin from 13 provinces in China. A novel <i>mcr-1</i> variant, named <i>mcr-1.3</i>, encoding an Ile-to-Val functional variant of MCR-1 was identified in a sequence type 155 (ST155) strain. An <i>mcr-1.3</i>-containing IncI2 plasmid, pHeN867 (60,757 bp), was identified. The transfer of pHeN867 led to a 32-fold increase in the MIC of colistin in the recipient, exhibiting an effect on colistin resistance that was similar to that of <i>mcr-1</i>.