Emergence and Genomic Features of a mcr-1 Escherichia coli from Duck in Hungary.

Plasmids carrying high-risk resistance mechanisms in pathogenic E. coli have gained particular attention in veterinary medicine, especially since the discovery of the colistin resistance gene, mcr-1 . Here, we provide the first evidence of its emergence and describe the complete mcr-1 plasmid sequence of a multi-resistant avian pathogenic E. coli (APEC) strain from waterfowl in Hungary. Whole-genome sequencing analysis and core-genome MLST were performed to characterize the genome structure of the mcr-1 plasmid and to reveal the phylogenetic relation between the Hungarian duck strain Ec45-2020 and the internationally circulating mcr-1 -positive E. coli strains from poultry and humans. Results showed that plasmid pEc45-2020-33kb displayed a high level of genome identity with mcr-1 plasmids of IncX4 type widespread among human, animal and food reservoirs of enteric bacteria of public health. The mcr-1 -positive E. coli strain Ec45-2020 belongs to the ST162 genotype, considered as one of the globally disseminated zoonotic genotypes of MDR E. coli . In accordance with international findings, our results underline the importance of continuous surveillance of enteric bacteria with high-risk antimicrobial resistance genotypes, including neglected animals, such as waterfowls, as possible reservoirs for the colistin resistance gene mcr-1 .