Pathogenesis of infections with Salmonella enterica subsp. enterica serovar Muenchen in the turtle Trachemys scripta scripta.

Abstract The pathogenesis of Salmonella enterica subsp. enterica serovar Muenchen infections in the aquatic turtle Trachemys scripta scripta was studied. After oral infection with 5×10 5  cfu of serovar Muenchen of 10–14-month-old turtles, kept at 26 °C, the intestine and especially the ileum, caecum and colon was colonized. Invasion of the intestinal wall, causing histopathological lesions, and colonization of internal organs were not observed. Serovar Muenchen was only isolated from turtles for 8 days after exposure. Keeping the turtles at 37 °C caused colonization of liver and spleen in two of six orally infected turtles and augmented the numbers of bacteria in the intestinal tract. In contrast to oral infections, intraperitoneal infections of turtles with serovar Muenchen enabled the bacterium to persist inside the host for at least 5 weeks. Clearance of serovar Muenchen from the liver and blood was more pronounced at 26 °C than at 37 °C. ELISA antibodies were demonstrated in intraperitoneally but not in orally infected turtles kept at 26 °C. In conclusion, the lack of persistence and invasiveness of serovar Muenchen in T. s. scripta after oral exposure might be due to the turtle’s relatively low body temperature and/or the absence of well-organized gut-associated lymphoid tissue.