Background: Intestinal bacterial infections are a major cause of morbidity and mortality, especially in neonates. Therefore, the aims of this study were to characterize Citrobacter rodentium infection in neonatal mice and determine the role played by specific probiotics in ameliorating disease severity.
Methods: Infection of C57BL/6 mice with C. rodentium was performed at postnatal day 14. A subset of mice was pretreated orally with either a mixture of Lactobacillus rhamnosus and Lactobacillus helveticus or placebo, starting at 7 days. To study the effects of B and T cells, rag1(-/-) and JH(-/-) mice were used, with survival, colonic crypt depth, and barrier function evaluated as outcome measures.
Results: C. rodentium infection caused weight loss and death. In contrast, survival was maintained by daily treatment with Lactobacilli. Weight loss, colonic epithelial cell hyperplasia, mucosal barrier dysfunction, and elevated serum corticosterone levels in C. rodentium-infected wild-type mice were ameliorated by probiotics, but not in rag1(-/-) animals. Beneficial effects of probiotics were observed in B cell-deficient (JH(-/-)) mice, indicating the requirement of T cells in reducing the adverse sequelae of neonatal enteric infection.
Conclusions: These findings demonstrate that C. rodentium infection in newborn mice causes death and that probiotics promote survival, but only in the presence of T cells.