Inc A/C plasmids are prevalent in multidrug-resistant Salmonella enterica isolates

A pulsed-field gel electrophoresis (PFGE) method was used to characterize a collection of 437 Salmonella enterica isolates from different animal sources for their antimicrobial resistance phenotypes and plasmid replicon types and gain insight into the distribution of multidrug resistance in relation to replicon types. The results indicated that some strains, particularly serovar Typhimurium and closely related types might have once carried the plasmid but the resistance genes were transferred to the chromosome with the subsequent loss of the plasmid.