Interactions of Salmonella enterica subsp. enterica serovar Muenchen with Intestinal Explants of the Turtle Trachemys scripta scripta

Abstract

Salmonella infections in reptiles, in contrast to those in birds and mammals, are limited to the intestinal tract. In this study, interactions of a strain of Salmonella enterica subsp. enterica serovar Muenchen (SEEM) with intestinal explants of the turtle Trachemys scripta scripta were examined by scanning electron microscopy (SEM). Adhesion and invasion in the chelonian intestinal explants at 30°C and 37°C were evaluated quantitatively. For purposes of comparison, the invasive capacity of SEEM in the continuous avian epithelial cell line DIV-1 at 30°C and 37°C was determined. Small numbers of M-like cells were found in the ileum of the turtles. The bacteria adhered mainly to the mucus of the intestinal explants. Only small numbers of salmonellae were associated with epithelial cells. Higher numbers of bacteria adhered at 30°C than at 37°C. Epithelial damage, embedding of bacteria in the epithelial surface and a ruffling-like process were noted only at 37°C. Minimal numbers of salmonellae invaded the explants at 30°C and 37°C. Invasion of DIV-1 cells was greater at 37°C than at 30°C. The study suggested that the intestinal mucous layer provides an important site of colonization for salmonellae in the chelonian host and protects the underlying epithelial cells.