Incidence of plasmid DNA in Salmonella strains isolated from clinical sources in Ontario, Canada, during 1979 and 1980.
Gel electrophoresis of DNA from 70 clinical strains of Salmonella revealed a heterogenous plasmid population. Plasmid DNA, ranging in molecular weight from 1.4 X 10(6) to 145 X 10(6), was demonstrated in 26 of 32 antibiotic-resistant strains. Several resistant strains carried up to six plasmids; however, of these, five strains which were multiply resistant contained a single plasmid of molecular weight 54 X 10(6) to 145 X 10(6). Only one incompatibility group H2 (IncH2) plasmid (pDT28) was detected in a strain of S. heidelberg; thus, this represents a reduction in the prevalence of these plasmids in Ontario Salmonella strains since 1974. The pDT28 plasmid resembled other IncH2 plasmids by its high molecular weight (145 X 10(6) ) and by virtue of its temperature-sensitive mode of transfer, resistance to tellurium, and inhibition of coliphage development. Of the 38 antibiotic-susceptible Salmonella strains, approximately half contained plasmids, ranging in molecular weight from 1.4 X 10(6) to 60 X 10(6). The plasmid-containing antibiotic-susceptible strains carried either a group of two to four small plasmids, with molecular weights less than 4.5 X 10(6), or a single large plasmid of molecular weight 23 X 10(6) or 60 X 10(6).
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003090:Coliphages / Q000254:growth & development; D004269:DNA, Bacterial; D004270:DNA, Circular; D006801:Humans; D008970:Molecular Weight; D009864:Ontario; D011815:R Factors; D012475:Salmonella / Q000187:drug effects / Q000235:genetics*; D012480:Salmonella Infections / Q000382:microbiology; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004270:DNA, Circular