High prevalence of the mcr-1 gene in retail chicken meat in the Netherlands in 2015.

Recently, plasmid-mediated colistin resistance was reported in humans, animals and food. We studied the presence of mcr-1 and mcr-2 in Dutch retail chicken meat. The prevalence of mcr-1 was 24,8% (53/214), whereas mcr-2 was not found. The presence of mcr-1-positive Enterobacteriaceae was confirmed by culture in 34/53 samples (64,2%). The prevalence depended on the supermarket chain and was lower in free-range chicken samples. The unexpected high prevalence of mcr-1 in food is cause for concern.