Complete sequence of a F2:A-:B- plasmid pHN3A11 carrying rmtB and qepA, and its dissemination in China.

Previous studies have confirmed that the spread of rmtB and qepA was mainly mediated by similar F2:A-:B- plasmids. In this study, a representative rmtB and qepA-harbouring F2:A-:B- plasmid, pHN3A11, originating from an Escherichia coli strain of feline origin, was fully sequenced and compared with other IncFII plasmids. pHN3A11 is 76,626bp long with a backbone similar to that of the IncFII plasmids obtained from China (pHK23a, pFOS-HK151325, pXZ) and Canada (pC15-1a). It contains genes encoding addiction (pemI/pemK, hok/mok/sok) and partitioning (parM, parB, and stbB) systems that promote plasmid maintenance during vertical transmission. rmtB, qepA, blaTEM-1, and dfr were found in previously observed contexts, interspersed with different complete or truncated insertion sequences and transposons (ΔIS1, ΔTn2, ΔintI1, ISCR3, 3 IS26, Tn21). Further analyses confirmed that pHN3A11-like plasmids have disseminated in E. coli isolates from pets, food animals and farm environments in China. The successful dissemination of F2:A-:B- type multidrug resistant plasmid among animals may represent a public health risk, and may further worsen the clinical impact.