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Title: Orally incoculated Salmonella typhimurium is detected in the lymph nodes and synovial fluid of swine

Author
item BROADWAY, PAUL - Texas Tech University
item BROOKS, J. - Texas Tech University
item Carroll, Jeffery
item DONALDSON, JANET - Mississippi State University
item Sanchez, Nicole
item SCHMIDT, TY - University Of Nebraska
item Brown, Tyson
item Callaway, Todd

Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2014
Publication Date: 7/1/2014
Citation: Broadway, P.R., Brooks, J.C., Carroll, J.A., Donaldson, J.R., Sanchez, N.C., Schmidt, T.B., Brown, T.R., Callaway, T.R. 2014. Orally incoculated Salmonella typhimurium is detected in the lymph nodes and synovial fluid of swine. American Meat Science Association Conference Reciprocal Proceedings. Pg. 225-226.

Interpretive Summary:

Technical Abstract: Salmonella is a foodborne pathogen that has been associated with illnesses from the consumption of meat products. Traditional carcass sampling techniques fail to account for contamination via atypical carcass reservoirs such as lymph nodes and synovial fluid that may harbor Salmonella. In this two-phase study, pigs at weaning (n = 36 from Phase 1; n = 38 from Phase 2) were orally inoculated with Salmonella typhimurium to investigate Salmonella migration from the gastrointestinal tract to peripheral lymph nodes and synovial fluid. Fecal samples were collected via terminal rectum swabs at 24, 48, and 72 h post-inoculation. Moreover, ileocecal, subiliac, popliteal, and mandibular lymph nodes as well as synovial fluid from the coxofemoral, shoulder, and stifle joints were collected at similar timepoints and cultured for the presence of the inoculated pathogen. Salmonella prevalence in feces tended to be greater in Phase 1 as compared to Phase 2 (P = 0.06; 52.78 vs. 31.58%). Salmonella prevalence in Ileocecal lymph nodes was 41.67% for pigs in Phase 1 and 37.00% for pigs in Phase 2. Both mandibular and subiliac lymph nodes were positive in 2.78% of pigs in Phase 1; however, inoculated Salmonella typhimurium was not detected in these lymph nodes in Phase 2. Examination of synovial fluid revealed 2.63% of pigs were positive in all sampled locations in Phase 2 but was not different from synovial fluid from Phase 1 pigs (P = 0.30). These results suggest it is possible for orally inoculated Salmonella typhimurium to migrate to musculoskeletal lymph nodes and synovial fluid. Bacterial contamination of these tissues could lead to contamination of food products if not managed properly at the processing plant. However, further research is needed to elucidate how Salmonella typhimurium infects these tissues to aid in the identification of pre-harvest interventions.