Complete sequences of IncU plasmids harboring quinolone resistance genes qnrS2 and aac(6′)-Ib-cr in Aeromonas spp. from ornamental fish

Abstract

The nucleotide sequences of three IncU plasmids from Aeromonas spp. isolated from ornamental fish are described. They had a typical IncU backbone for plasmid replication and maintenance functions, but conjugative transfer modules were disrupted. The gene qnrS2 was inserted into mpR as a mobile insertion cassette. Novel Tn3 family transposons carrying putative toxin-antitoxin and plasmid stability genes were identified. The study demonstrates high plasticity of IncU plasmids from aquatic environments.