Effects of tetracycline and a CMY-2 plasmid on colonization and fecal shedding of Salmonella in pigs

This thesis reports an investigation of the in vitro characterization of certain Salmonella strains and dissemination of the strains in vivo. The in vivo section of this research focused on the effect of tetracycline on the dissemination of Salmonella Typhimuriim in pigs and the effect of a multiple-drug resistant CMY-2 plasmid on dissemination.The Salmonella Typhimurium inoculum was orally administered to one pig in each pen and qualitative and quantitative measurements of colonization and shedding were taken over a seven-day period. Pens were treated with either blaCMY-2 positive or a blaCMY-2 negative Salmonella Typhimurium strain, and also received either tetracycline or no tetracycline. There was no statistically significant difference in dissemination of Salmonella among pigs in the tetracycline treated and non-treated pens. However there was a significantly higher level of colonization and shedding in pigs treated with the blaCMY-2 positive Salmonella Typhimurium strain compared to the pigs treated with the blaCMY-2 negative Salmonella Typhimurium strain.