Sequencing and comparative genomics analysis of the IncHI2 plasmids pT5282-mphA and p112298-catA and the IncHI5 plasmid pYNKP001-dfrA

•Complete sequences of plasmids pT5282-mphA, p112298-catA and pYNKP001-dfrA were determined.•A scheme for typing IncHI plasmids into five separately clustering subgroups (IncHI1–5) was proposed.•Considerable genetic conservation was observed within the backbone sequences of the IncHI2 and the IncHI5 subgroups.•The backbone sequences of the IncHI2 and IncHI5 subgroups were dramatically different from each other.•The plasmids accrued varied accessory regions composed of integrons, transposons, insertion sequences and resistance genes.