Co-existence of two novel phosphoethanolamine transferase gene variants in Aeromonas jandaei from retail fish

Abstract Two novel phosphoethanolamine transferase genes, eptAv7 and eptAv3, were identified in the chromosome of an Aeromonas jandaei isolate recovered from retail fish. The variants showed 79.9% and 80.0% amino acid identity to MCR-7.1 and MCR-3.1, respectively, and could increase colistin resistance 128- to 256-fold in Aeromonas salmonicida. The flanking region of two variants, which are absent for any mobile genetic elements, were also observed in other Aeromonas species. This finding supports the view that Aeromonas is a reservoir for MCR-3 and MCR-7 mobile colistin resistance.