Damage to the intestinal epithelial barrier by antibiotic pretreatment of salmonella-infected rats is lessened by dietary calcium or tannic acid

Perturbation of the intestinal microbiota by antibiotics predisposes the host to food-borne pathogens like Salmonella. The effects of antibiotic treatment on intestinal permeability during infection and the efficacy of dietary components to improve resistance to infection have not been studied. Therefore, we investigated the effect of clindamycin on intestinal barrier function in Salmonella-infected rats. We also studied the ability of dietary calcium and tannic acid to protect against infection and concomitant diarrhea and we assessed intestinal barrier function. Rats were fed a purified control diet including the permeability marker chromium EDTA (CrEDTA) (2 g/kg) or the same diet supplemented with calcium (4.8 g/kg) or tannic acid (3.75 g/kg). After adaptation, rats were orally treated with clindamycin for 4 d followed by oral infection with Salmonella enteritidis. Two additional control groups were not treated with antibiotics and received either saline or Salmonella. Urine and feces were collected to quantify intestinal permeability, diarrhea, cytotoxicity of fecal water, and Salmonella excretion. In addition, Salmonella translocation was determined. Diarrhea, CrEDTA excretion, and cytotoxicity of fecal water were higher in the clindamycin-treated infected rats than in the non-clindamycin-treated infected control group. Intestinal barrier function was less in the Salmonella-infected rats pretreated with antibiotics compared with the non-clindamycin- treated rats. Both calcium and tannic acid reduced infection-associated diarrhea and inhibited the adverse intestinal permeability changes but did not decrease Salmonella colonization and translocation. Our results indicate that calcium protects against intestinal changes due to Salmonella infection by reducing luminal cytotoxicity, whereas tannic acid offers protection by improving the mucosal resistance.