In the present study, we show that virulence-resistance plasmids from emerging multidrug-resistant isolates of Salmonella enterica serovar Typhimurium were derived from a virulence-associated plasmid. The virulence-associated plasmid is essential for systematic invasiveness of S. Typhimurium in mice (pSLT) and, through the acquisition of a large insert containing a resistance island flanked by IS1294 elements, this plasmid plays a role in multidrug resistance. A blaCMY-2-carrying plasmid from a cefotaxime-resistant isolate comprised a segment of Escherichia coli plasmid pAR060302 and the replication region (IncFIB) of a virulence-resistance plasmid. These results provide insights into the evolution of drug resistance in emerging clones of S. Typhimurium.
(Dairy Hygiene Research Division)
Tamamura,Y. et al (2013) PLoS One. 14;8(10):e77644