title: RSF1010-like plasmids in Australian Salmonella enterica serovar Typhimurium and origin of their sul2-strA-strB antibiotic resistance gene cluster.
abstract: Salmonella enterica serovar Typhimurium phage type 9 isolates resistant to streptomycin and sulfonamide have been recovered from both bovine and human sources in Australia. This study aimed to identify the resistance genes and their location. Polymerase chain reaction was used to screen for resistance genes and sul2 (sulphonamide resistance) and strA and strB (streptomycin resistance) were detected. A small streptomycin and sulfonamide resistance plasmid carrying the three resistance genes was recovered from these isolates by transformation and was shown to be essentially identical to the small IncQ plasmid RSF1010. The sequences of one plasmid, pSRC15, and RSF1010 differed at only a few positions that may be errors in the older sequence. RSF1010 has been recovered from many species and in many countries since its first isolation in the early 1970s. We conclude that this plasmid has persisted unchanged in the environment for over 30 years. The antibiotic resistance gene cluster containing strA, strB, and sul2 genes has clearly arisen from other known entities by a combination of transposition and homologous recombination using a short segment of homology. This resistance gene cluster is now widely distributed in plasmids and genomic islands in a number of contexts.
authors.affiliation: School of Molecular Bioscience, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Sheree
authors.initials: S
authors.lastname: Yau
authors.forename: Xiulan
authors.initials: X
authors.lastname: Liu
authors.forename: Steven P
authors.initials: SP
authors.lastname: Djordjevic
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Hall
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002417:Cattle; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D044404:Genomic Islands; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D005810:Multigene Family; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012480:Salmonella Infections / Q000382:microbiology; D012481:Salmonella Infections, Animal / Q000382:microbiology; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics; D017422:Sequence Analysis, DNA; D013307:Streptomycin / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C491369:Sul2 protein, bacteria; D013449:Sulfonamides; D013307:Streptomycin