Transferable colistin resistance encoding gene mcr-1 not detected in E. coli isolated from humans and retail meats in Ireland

Background and Objectives The plasmid-mediated colistin resistance gene, mcr-1, was first described in November 2015 by Liu et al in E. coli isolated from food, animals and humans. Subsequently, others have isolated E. coli... [ view full abstract ]

Background and Objectives
The plasmid-mediated colistin resistance gene, mcr-1, was first described in November 2015 by Liu et al in E. coli isolated from food, animals and humans. Subsequently, others have isolated E. coli harbouring mcr-1 from human animal and food specimens. This finding is concerning as plasmids can transfer easily between different genera of bacteria, raising concerns for the rapid and widespread dissemination of colistin resistance.
Methods
Whole genome sequences of 96 E. coli isolates collected from retail meats in Ireland and Northern Ireland (November 2013 - September 2014) and 96 E.coli isolates collected (2005 – 2011) primarily from residents of long term care facilities were examined. Genomes were hosted in and analysis was performed using a local installation of BIGSdb. The mcr-1 sequence of Liu et al was used to conduct a BLASTN search against all 192 Irish human and food E. coli genomes.
Results
No significant matches were returned indicating the absence of the gene in this set of genomes.
Conclusions
The absence of mcr-1 in this limited collection of food and human genomes suggests that it has not yet been disseminated widely in food animals or humans in Ireland. Use of colistin and related compounds in human health care on the island of Ireland is very limited. The recent finding of a transferable colistin resistance mechanism in China and more recently in Europe and North America is of major concern and underlines the necessity of continuous surveillance.