11.02.2016

Prior to 2015, the mechanism of resistance to colistin was only known to involve chromosomal mutations, and so its spread was expected to be limited to vertical transmission. In 2015 however, the first plasmid-mediated colistin resistance involving the mrc-1 gene was discovered in China.
Prompted by these reports of mrc-1-mediated colistin resistance, colistin resistance was investigated in 1,696 isolates collected from 2007 to 2014 within the frame of the French livestock antimicrobial resistance surveillance programme. The mcr-1 gene was detected in all commensal Escherichia coli isolates with a minimum inhibitory concentration to colistin above the 2 mg/L cut-off value (n=23). In poultry, mcr-1 prevalence was 5.9% in turkeys and 1.8% in broilers in 2014. These findings support that mcr-1 has spread in French poultry.