title: Influence of antibiotic-supplemented feed on occurrence and persistence of Salmonella typhimurium in experimentally infected swine.
abstract: The effect of chlortetracycline given at a concentration of 220.5 g/metric ton of feed and of a combination product which supplies chlortetracycline (110.2 g/metric ton), sulfamethazine (110.2 g/metric ton), and penicilin G (55.1 g/metric ton) on the occurrence and persistence of Salmonella typhimurium in experimentally infected swine was studied. Weanling pigs (av weight, 8.2 kg) were inoculated via the feed with 10(11) colony-forming units of S typhimurium 298-1NA. An equal number of nonexposed swine given identical treatment were used as controls. Infected pigs had increased temperatures (maximal av, 41 C) for the first 4 days after infection and severe diarrhea during the first 21 days. The use of chlortetracycline and a combination product at subtherapeutic concentrations in feed did not increase the Salmonella pool or prolong the carrier state in swine. A decrease in number of Salmonella shed from swine given chlortetracycline at the concentration of 220.5 g/metric ton was observed. Significant differences did not occur in Salmonella-related deaths or in emergence of multiple antibiotic-resistant Salmonella by antibiotic selection or R factor transfer. Zoonotic transmission of the infecting Salmonella to animal caretakers was not detected.
mesh_terms: D000284:Administration, Oral; D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002751:Chlortetracycline / Q000494:pharmacology; D003967:Diarrhea / Q000382:microbiology / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D005260:Female; D008297:Male; D010400:Penicillin G / Q000494:pharmacology; D010403:Penicillin Resistance; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects / Q000302:isolation & purification*; D013418:Sulfamethazine / Q000494:pharmacology; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D013418:Sulfamethazine; D010400:Penicillin G; D002751:Chlortetracycline