title: Evaluation of an Alternative Experimental Infection Method, Which Closely Mimics the Natural Route of Transmission of Monophasic Salmonella Typhimurium in Pigs.
abstract: Salmonella carriage in pigs is a significant food safety issue. This study describes a new protocol of Salmonella infection based on exposure to an artificially contaminated environment that closely mimics natural exposure to the organism. The aim of the study was to develop and evaluate the effectiveness of this protocol, which could then be used as a tool in the investigation of control measures. In addition, Salmonella shedding pattern and growth performance of the pigs were examined. Trial pigs (n = 10) were placed in a pen that had been previously contaminated by housing two pigs experimentally challenged with a monophasic Salmonella Typhimurium (mST). A further 10 pigs were placed in a Salmonella-free pen. Pigs were weighed on days 0 and 28. Feces was collected on days 0, 2, 3, 5, 7, 14, 21, and 28 and examined for the presence and quantity of Salmonella. The trial was replicated once. All pigs in the contaminated pens shed Salmonella within the first 2 days of exposure with values ranging from 100to 104CFU/g. The noninfected pigs had significantly higher final body weights on day 28 than those exposed to the Salmonella contaminated environment in both replicates. The pigs in the Salmonella-free pen had significantly higher average daily weight gain over the 28-day period compared to the infected animals (p < 0.001). Although not significant, numerical improvements in average daily feed intake and feed conversion efficiency were observed in the Salmonella-free pigs when compared to the contaminated pigs. The approach used was successful in infecting pigs with Salmonella without the need for direct inoculation or exposure to seeder pigs. This "natural" method of infection in which pigs are exposed to low levels of environmental contamination with Salmonella may be an effective tool that could be utilized when investigating control measures.
authors: 1 Food Safety Department, Teagasc Food Research Centre Ashtown , Dublin, Ireland .|2 UCD Veterinary Sciences Centre, University College Dublin , Dublin, Ireland .
authors: Helen
authors: H
authors: Lynch
authors: 1 Food Safety Department, Teagasc Food Research Centre Ashtown , Dublin, Ireland .
authors: Hector
authors: H
authors: Argüello
authors: 1 Food Safety Department, Teagasc Food Research Centre Ashtown , Dublin, Ireland .|3 Department of Science, Waterford Institute of Technology , Waterford, Ireland .
authors: Kavita
authors: K
authors: Walia
authors: 4 Teagasc , Pig Development Department, Moorepark, Ireland .
authors: Peadar G
authors: PG
authors: Lawlor
authors: 1 Food Safety Department, Teagasc Food Research Centre Ashtown , Dublin, Ireland .
authors: Geraldine
authors: G
authors: Duffy
authors: 3 Department of Science, Waterford Institute of Technology , Waterford, Ireland .
authors: Gillian E
authors: GE
authors: Gardiner
authors: 2 UCD Veterinary Sciences Centre, University College Dublin , Dublin, Ireland .
authors: Finola C
authors: FC
authors: Leonard
mesh_terms: D000818:Animals; D057138:Bacterial Shedding; D015169:Colony Count, Microbial; D005240:Feasibility Studies; D005243:Feces / Q000382:microbiology; D005260:Female; D015203:Reproducibility of Results; D012481:Salmonella Infections, Animal / Q000635:transmission*; D012486:Salmonella typhimurium / Q000302:isolation & purification*; D013552:Swine / Q000382:microbiology*; D013553:Swine Diseases / Q000382:microbiology / Q000635:transmission*
keywords: Salmonella; infection protocol; monophasic Salmonella Typhimurium.; pig