Long term survival and infectivity of Salmonella Choleraesuis

It is believed that Salmonella Choleraesuis, the host-adapted serotype of s wine, does not survive well outside the host. We examined the survival capa bility as well as the presence of latent DNA of S. Choleraesuis in swine fe ces. Pigs were infected with S. Choleraesuis and feces was collected and po oled on days 2, 4, 7, and 10 post inoculation (PI). Feces was stored in a w et and a dry form and survival was measured over 13 months. Salmonella Chol eraesuis was recovered from wet feces through 3 months of storage. In a des iccated (dry) form, S. Choleraesuis was recovered from at least 13 months. Direct PCR analysis did not detect S. Choleraesuis subsequent to the final culture recovery for any stored sample. We also examined the infectivity of S. Choleraesuis resident in dry feces. Six or 13 week old pigs were inocul ated with dry feces that had been stored either 2 months or 4 months, respe ctively. Pigs were inoculated either intranasally or by mixing dry feces wi th the swine ration, Although clinical signs were mild, S. Choleraesuis was widely disseminated among the tissues of all the pigs inoculated. This stu dy demonstrates that S. Choleraesuis remains viable and infective in the en vironment. Therefore, contaminated fecal matter can serve as a reservoir fo r S. Choleraesuis as well as other Salmonella spp. Control measures must co nsider this environmental reservoir as a source of new infections.