Effects of the antimicrobial growth promoter tylosin on subclinical infection of pigs with Salmonella enterica serotype Typhimurium.
OBJECTIVE
To determine whether feeding tylosin, an antimicrobial growth promoter, to pigs was associated with increased risk of infection with and excretion of Salmonella enterica serotype Typhimurium.


METHODS
17 healthy pigs.


METHODS
A commercial pelleted dry feed was given in 2 feeding trials. In trial A, 11 pigs were given feed with tylosin, 11 pigs were given feed without tylosin, and 11 pigs were given feed with tylosin before and feed without tylosin after inoculation with S Typhimurium. In trial B, 44 pigs were given feed that contained tylosin, and 44 pigs were given feed without tylosin. Three weeks after the start of each trial, pigs were orally inoculated with approximately 5 x 10(6) colony-forming units of S Typhimurium. Feces were examined for S Typhimurium, using semiquantitative microbiologic techniques before and for 5 or 6 weeks after inoculation. Serum antibody titers against S enterica were measured by use of ELISA.


RESULTS
None of the pigs developed clinical signs of salmonellosis. However, after inoculation, S Typhimurium was isolated from feces of most pigs, and all but 2 pigs developed serum antibodies against S enterica. Significant differences were not detected between experimental and control groups in either trial.


CONCLUSIONS
Results indicate that tylosin fed as an antimicrobial growth promoter to pigs may not be an important factor in promoting infection with or excretion of S enterica serotype Typhimurium.
Baggesen
D L
DL
Danish Veterinary Laboratory, Copenhagen.
Wingstrand
A
A
Carstensen
B
B
Nielsen
B
B
Aarestrup
F M
FM
D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D005243:Feces / Q000382:microbiology; D005260:Female; D008297:Male; D012481:Salmonella Infections, Animal / Q000517:prevention & control*; D019779:Salmonella enterica / Q000145:classification / Q000235:genetics; D012486:Salmonella typhimurium / Q000302:isolation & purification; D012703:Serotyping; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology / Q000517:prevention & control*; D015645:Tylosin / Q000008:administration & dosage / Q000627:therapeutic use*
D000900:Anti-Bacterial Agents; D015645:Tylosin