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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Livestock Issues Research » Research » Publications at this Location » Publication #304960

Title: Salmonella prevalence of lymph nodes and synovial fluid of orally inoculated swine

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

Submitted to: Agriculture, Food and Analytical Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2014
Publication Date: 5/15/2015
Citation: Broadway, P.R., Carroll, J.A., Brooks, J.C., Donaldson, J.R., Sanchez, N.C., Schmidt, T.B., Brown, T.R., Callaway, T.R. 2015. Salmonella prevalence of lymph nodes and synovial fluid of orally inoculated swine. Agriculture, Food and Analytical Bacteriology. 5(1):6-8.

Interpretive Summary: Illnesses associted with Salmonella were the most commonly reported foodborne bacterial infection in 2011 (16.42 cases per 100,000 people) despite efforts to reduce the incidence of this foodborne pathogen below that reported in 2010 (6.8 cases per 100,000 people; CDC, 2010). In an effort further aid in understanding how to reduce the incidences of this food borne pathogen, scientists from ARS' Livestock Issues Research Unit, ARS' Food and Feed Safety Research Unit, Texas Tech University, Mississippi State University, and the University of Nebraska conducted a collaborative study to evaluate the potential migration of Salmonella into peripheral tissues of the pigs. Results from this study determined that experimental oral inoculation of pigs with Salmonella may result in Salmonella penetrating the lymphatic system and reaching peripheral lymph nodes. While most of the infection was localized to the illeocecal lymph nodes and feces, the infection was also shown to reach peripheral lymph in some animals. Additionally, it was shown that oral infection with Salmonella may be able to cause infection in the joints of immunocompromised animals. Understanding the transmission routes of Salmonella to peripheral tissues in the carcasses of pigs that enter the food chain is vital to the establishment of interventions and control points to prevent foodborne illness and cross contamination in the pork production process. More research needs to be conducted to determine how Salmonella infections with different routes of entry migrate through the lymphatic system and how these infections impact animal health and food safety. The results from this study will be of particular interest to scientists working in the areas of food safety, livestock health and immunity, and meat processing.

Technical Abstract: Salmonella is a foodborne pathogen that may be associated with the consumption of meat products. Failure of current interventions to control Salmonella in the food supply of the U.S. has led researchers to believe that atypical carcass reservoirs may be responsible for harboring this pathogen. In this two phase study, pigs (n = 36/Phase 1; n = 38/Phase 2) were experimentally infected orally with Salmonella typhimurium to monitor the migration pattern of the given bacteria. Fecal samples were collected at 24, 48, and 72 h post-infection and tested for the presence of the experimentally infected Salmonella. Ileocecal, subiliac, popliteal, and mandibular lymph nodes were collected, and synovial fluid was collected from the coxofemoral, shoulder, and stifle joints at the same post-infection timepoints to test for the experimentally infected bacteria. Fecal prevalence tended to be greater in Phase 1 (P = 0.06; 52.78 vs. 31.58%). Ileocecal lymph node prevalence was 41.67% for Phase 1 and 37.00% for Phase 2. Both mandibular and subiliac lymph node prevalence was determined 2.78% in Phase 1; however, no Salmonella was detected in Phase 2.Examination of synovial fluid yielded a prevalence of 2.63% in all locations (from a single pig) in Phase 2 but was not different from Phase 1 (P = 0.30) in which no samples were positive for Salmonella. These results suggest that it is possible for orally contracted Salmonella has the ability to migrate to musculoskeletal lymph nodes. These areas may lead to cross-contamination of food products. Further research is needed to determine routes and migration patterns of Salmonella from the gastrointestinal tract to peripheral tissues to further elucidate how these infections impact food safety.