IntroductionThe emergence of carbapenem-resistant bacteria causing serious infections may lead to more frequent use of previously abandoned antibiotics like colistin. However, mobile colistin resistance genes (mcr) can jeopardise its effectiveness in both human and veterinary medicine. In Germany, turkeys have been identified as the food-producing animal most likely to harbourmcr-positive colistin-resistant Enterobacterales (mcr-Col-E). Therefore, the aim of the present study was to assess the prevalence of bothmcr-Col-E and carbapenemase-producing Enterobacterales (CPE) in German turkey herds and humans in contact with these herds.MethodsIn 2018 and 2019, 175 environmental (boot swabs of turkey faeces) and 46 human stool samples were analysed using a combination of enrichment-based culture, PCR, core genome multilocus sequence typing (cgMLST) and plasmid typing.Resultsmcr-Col-E were detected in 123 of the 175 turkey farms in this study (70.3%).mcr-Col-E isolates wereEscherichia coli(98.4%) andKlebsiellaspp. (1.6%). Herds that had been treated with colistin were more likely to harbourmcr-Col-E, with 82.2% compared to 66.2% in untreated herds (p= 0.0298). Prevalence also depended on husbandry, with 7.1%mcr-Col-E in organic farms compared to 74.5% in conventional ones (p< 0.001). In addition, four of the 46 (8.7%) human participants were colonised withmcr-Col-E.mcr-Col-E isolates from stables had minimum inhibitory concentrations (MICs) from 4 to ≥ 32 mg/l, human isolates ranged from 4 to 8 mg/l. cgMLST showed no clonal transmission of isolates. For one farm, plasmid typing revealed great similarities between plasmids from an environmental and a human sample. No CPE were found in turkey herds or humans.DiscussionThese findings confirm thatmcr-Col-E-prevalence is high in turkey farms, but no evidence of direct zoonotic transmission of clonalmcr-Col-E strains was found. However, the results indicate that plasmids may be transmitted betweenE. coliisolates from animals and humans.