INFLUENCE OF ANTIBIOTIC-SUPPLEMENTED FEED ON OCCURRENCE AND PERSISTENCE OF SALMONELLA-TYPHIMURIUM IN EXPERIMENTALLY INFECTED SWINE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 37  (6) , 649-655
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 penicillin G (55.1 g/metric ton) on the occurrence and persistence of S. typhimurium in experimentally infected swine was studied. Weanling pigs (av [average] weight, 8.2 kg) were inoculated via the feed with 1011 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.degree. C) for the 1st 4 days after infection and severe diarrhea during the 1st 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 the 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.