Effects of kanamycin administration to poultry on the interspecies transmission of drug-resistant Salmonella

Three experiments were conducted to assess the relationship between antibiotic administration to poultry and the transmission of drug-resistant Salmonella through a simulated food chain. Poults were inoculated per os with either multiply drug-resistant Escherichia coli and drug-sensitive S. typhimurium or with multiply drug-resistant S. typhimurium. One-half of the poults inoculated with drug-sensitive S. typhimurium and all poults given drug-resistant S. typhimurium received kanamycin in their drinking water. Liver tissue from these poults was incorporated into diets fed to rats, half of which were treated with kanamycin. Antibiotic administration to the poults was associated with a significantly (P less than .05) higher frequency of transmission of drug-resistant S. typhimurium to the rats through the simulated food chain. S. typhimurium was isolated only from rats treated with kanamycin. The highest frequency of isolation of drug-resistant S. typhimurium from rats (40%) was observed in kanamycin-treated rats fed a diet containing liver from kanamycin-treated poults. Results of this experiment indicate that antibiotic administration can increase the frequency of transmission of drug-resistant Salmonella through the food chain.