All animal experiments were approved by the Institutional Animal Care and Use Committee. Probiotic L. acidophilus (La) was cultured in deMan, Rogosa, and Sharpe broth (MRS; Difco, Detroit, MI) and grown at 37 °C for 20 h and re-suspended selleck chemical in PBS prior to oral inoculation (1 × 109 CFU per mouse). Citrobacter rodentium (strain DBS100; American Type Culture Collection number 51459) was grown overnight in Luria broth (LB) and subsequently re-suspended in PBS prior to dosing (0.5 mL per mouse; approximately 5 × 108 CFU
of C. rodentium per mouse). Citrobacter rodentium (Cr) antigen was prepared by collecting an overnight culture of Cr in LB. The bacterial culture was washed in PBS and sonicated on ice. The homogenate was then centrifuged (6000 g) at 4 °C for 30 min. Supernatants were collected, and the protein concentration
was determined. Three independent experiments were conducted in which neonatal (3 days of age) mice and lactating dams were randomly divided BGB324 in vivo into five groups of approximately 7–10 pups per treatment (Fig. 1): group A (nontreated normal control mice), group B (C. rodentium inoculated), group C (prebiotic inulin treated + C. rodentium), group D (probiotic L. acidophilus + C. rodentium), group E (synbiotic combination probiotic L. acidophilus + prebiotic inulin + C. rodentium). Mice of treatment group D were administered L. acidophilus (approximately 1 × 109 CFU per mouse) twice weekly by intragastric gavage for approximately 7 weeks. Sterile water was supplemented with prebiotic: inulin and oligofructose (1 g per 100 mL, Raftilose Synergy®) and administered by intragastric gavage three times weekly from 1 to 3 weeks of age and administered in drinking water provided ad libitum from weeks 3 to 7 weeks of age for mice of treatment group C, with fresh inulin-supplemented
drinking water provided every 2 days. Mice of treatment group E were administered a synbiotic combination of L. acidophilus, approximately 1 × 109 CFU per mouse and prebiotic inulin (1 g per 100 mL) by intragastric gavage two times per week from 1 to 7 weeks selleck compound of age. Control mice (group A) only received a saline vehicle bi-weekly over the duration of the experiment. At 5 weeks of age, mice of treatment groups B, C, D, and E were orally inoculated by intragastric gavage with enteric pathogen, C. rodentium. All mice were sacrificed at 7 weeks of age. To assess the clearance of Cr, fecal pellets were collected from each mouse weekly postinfection. Fecal pellets were weighed, homogenized, serially diluted, and plated on selective MacConkey agar plates for gram-negative organisms (Chen et al., 2005; Johnson-Henry et al., 2005; Wu et al., 2008). Bacterial colonies were enumerated after overnight incubation at 37 °C.