Chromosome-mediated mcr-3 variants in aeromonas veronii from chicken meat

Abstract

Two adjacent colistin resistance gene variants, termed mcr-3.3 and mcr-3-like, were identified in the chromosome of an Aeromonas veronii isolate obtained from retail chicken meat. The variants showed 95.20% and 84.19% nucleotide sequence identity, respectively, to mcr-3 from porcine Escherichia coli. Functional cloning indicated that only mcr-3.3 conferred polymyxin resistance in both E. coli and Aeromonas salmonicida. The mcr-3.3-mcr-3-like segment was also observed in other Aeromonas species, including A. media, A. caviae, and A. hydrophila.