Plasmid with Colistin Resistance Gene <i>mcr-1</i> in Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains Isolated from Pig Slurry in Estonia

Abstract

ABSTRACT A plasmid carrying the colistin resistance gene mcr-1 was isolated from a pig slurry sample in Estonia. The gene was present on a 33,311-bp plasmid of the IncX4 group. mcr-1 is the only antibiotic resistance gene on the plasmid, with the other genes mainly coding for proteins involved in conjugative DNA transfer ( taxA , taxB , taxC , trbM , and the pilX operon). The plasmid pESTMCR was present in three phylogenetically very different Escherichia coli strains, suggesting that it has high potential for horizontal transfer.