Salmonella enterica serovar Typhimurium continues to be a major cause of foodborne illness worldwide and pork can serve as a source of infection. Co-infection of S. enterica with Lawsonia intracellularis, a common intestinal pathogen of swine, has been found as risk factor for increased S. enterica shedding. The objective of this study was to investigate if vaccination against L. intracellularis could lead to decreased S. Typhimurium shedding. To test this hypothesis, pigs were challenged with either S. Typhimurium or S. Typhimurium and L. intracellularis, with and without L. intracellularis vaccination (n = 9 per group). A non-challenged group served as a negative control. Vaccination decreased the shedding of S. Typhimurium in co-infected animals by 2.12 log10 organisms per gram of feces at 7 days post infection. Analysis of the microbiome showed that vaccination led to changes in the abundance of Clostridium species, including Clostridium butyricum, in addition to other compositional changes that may explain the protection mediated against S. Typhimurium. These results indicate that vaccination against L. intracellularis in co-infected herds may provide a new tool to increase food safety by helping to prevent S. enterica without the need for antibiotics.
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We would like to thank Trevor Gould from the University of Minnesota Informatics Institute (UMII) for his assistance in generating the OTU table for analysis and Aaron Rhendal for his assistance in statistical analysis of shedding data. For help in collection of samples and technical assistance we wish to thank: Fabian Chamba, Talita Resende, Yonghyan Kim, Luiza Roos, Jorge Garrido, Britta Wass, Kyrstin Danielson, Grace Moores and Jackelyn Goldschmidt. We would like to thank Dana Beckler for preparation of the Lawsonia intracellularis culture and assistance in challenge of animals. We would also like to thank the University of Minnesota Genomics Center for sequencing of samples for microbiome analysis. This work was supported by USDA-AFRI grant 1005423.
© 2018 The Author(s).