DOES AN INFLAMMATORY MECHANISM CONTRIBUTE TO SALMONELLA SEROTYPE TYPHIMURIUM-INDUCED DIARRHEA?
Histopathological evaluation of calf intestinal tissue collected between 18 and 48 h after oral infection with Salmonella serotype Typhimurium reveals necrosis of the uppermost mucosa with complete loss of the intestinal epithelium and discernible villi or crypt structures (Fig. (Fig.2F)2F) (99). The loss of epithelial cells often affects large surface areas and, in severe cases, covers 3 to 4 m of the terminal ileum and the cranial 1 to 2 m of the colon. The absence of epithelial cells in large areas of the intestine in calves with acute diarrhea raises questions about the importance of chloride secretion by epithelial cells during the pathogenesis of enterocolitis. The intestinal pathology suggests that the increased vascular permeability accompanying inflammation in combination with the loss of epithelial integrity could lead to diarrhea by an exudative mechanism (i.e., flow of water and solutes from the blood to the intestinal lumen as a consequence of inflammation).
