Occurrence of Salmonella serotype Typhimurium DT104 on a commercial swine farm before, during, and after depopulation and repopulation.
OBJECTIVE
To determine whether depopulation-repopulation could be used to eradicate Salmonella serotype Typhimurium DT104 from a commercial swine farm in the midwestern United States.


METHODS
Observational study


METHODS
A commercial swine farm undergoing depopulation-repopulation to eliminate porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae.


METHODS
Pooled fecal samples, tissue samples, and serum samples were collected from pigs on the farm before and after depopulation-repopulation. When there were no pigs on the farm, environmental swab specimens were collected for bacterial culture. Serum was analyzed for anti-Salmonella antibodies with an indirect ELISA. Salmonella isolates obtained by bacterial culture of fecal, tissue, and environmental samples were characterized by means of serotyping, phage typing, pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing.


RESULTS
167 Salmonella isolates representing 9 serotypes were recovered from the farm. Results of PFGE and antimicrobial susceptibility testing suggested that S. Typhimurium DT104 strain was not eradicated from the farm. However, seroprevalence of anti-Salmonella antibodies and the percentage of pooled fecal samples positive for Salmonella spp were significantly decreased following repopulation.


CONCLUSIONS
Results suggested that depopulation-repopulation in conjunction with stringent cleaning and disinfection, attention to biosecurity procedures, control of other diseases, and changes in feed management may reduce the occurrence of, but likely will not eliminate, Salmonella spp in commercial swine herds.
Erdman
Matthew M
MM
Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
Harris
Isabel T
IT
Torremorell
Montserrat
M
Wilt
Vincil M
VM
Harris
D L Hank
DL
D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D004197:Disease Reservoirs / Q000662:veterinary*; D004783:Environmental Microbiology; D005260:Female; D006920:Hygiene; D015995:Prevalence; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000517:prevention & control; D012486:Salmonella typhimurium / Q000276:immunology / Q000302:isolation & purification; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000517:prevention & control
D000907:Antibodies, Bacterial