The recent discovery of ciprofloxacin-resistant Salmonella enterica serovar Typhimurium infections in humans has increased concern regarding the use of antimicrobials in food animals. It is because of this concern that many drugs are no longer available for use in food animal medicine, in an attempt to limit the spread of resistant organisms from animals to humans. The mar (multiple antibiotic resistance) system, originally found in E. coli, confers resistance to many different classes of drugs through efflux and porin resistance mechanisms, in response to unrelated compounds. The detection of this system in Salmonella Typhimurium, combined with the increasing resistance patterns and common transmission through improperly prepared food products, points to the possibility that antimicrobial use of any kind in food animals may lead to resistant infections in humans. In this research Salmonella Typhimurium was exposed to the commonly used antibiotic oxytetracycline both in vitro and in vivo, using a tissue chambVeterinary Pathobiolog
