Distinctive human and swine strains of Salmonella enterica serotype Wien carry large self-transferable R-plasmids. A plasmid contains a class 1-qacEΔ1–sul1 integron with the dfrA1–aadA1a cassette configuration Original Research Article

The genetic base of the multi-drug resistance of Salmonella serotype Wien (S. Wien) strains, containing large plasmids and collected from human faeces and raw-pork and generating distinctive DNA-fingerprinting (PFGE- and/or RAPD-profiles), was analysed. Two types of self-transferable R-plasmids were identified, which contain the tem1, [catA1, cmlA1], aphA1, sul1 and sulII, aadA1a, tet(B), and dfrA1 genes, respectively, encoding resistance to ampicillin–carbenicillin–oxacillin–cefazoline–ceftazidime–amoxicillin/clavulanic-acid, chloramphenicol, kanamycin–neomycin, sulfadiazine, streptomycin–spectinomycin, tetracycline and trimethoprim. In addition, both carried a class 1-qacEΔ1–sul1 integron without gene cassettes (In0), and one of them a second class 1-qacEΔ1–sul1 integron with dfrA1 and aadA1a gene cassettes. These data point towards a new alert regarding the selection of multi-drug-resistant zoonotic bacteria causing foodborne disease.