Salmonella in Swine: Microbiota Interactions

For the important foodborne pathogen Salmonella enterica to cause disease or persist in pigs, it has evolved an intricate set of interactions between itself, the host, and the indigenous microflora of the host. S. enterica must evade the host's immune system and must also overcome colonization resistance mediated by the pig's indigenous microflora. The inflammatory response against S. enterica provides the bacteria with unique metabolites and is thus exploited by S. enterica for competitive advantage. During infection, changes in the composition of the indigenous microflora occur that have been associated with a breakdown in colonization resistance. Healthy pigs that are low-level shedders of S. enterica also exhibit alterations in their indigenous microflora similar to those in ill animals. Here we review the literature on the interactions that occur between swine, S. enterica, and the indigenous microflora and discuss methods to reduce or prevent colonization of pigs with S. enterica.