E. faecalis prevents C. jejuni colonization of CBA/J mice. CBA/J mice were treated with ampicillin, followed by oral gavage with PBS, E. faecalis KLC3001, and L. acidophilus NCFM, and then challenged with either PBS (uninfected) or C. jejuni after 48 h. At 7 dpi, the mice were euthanized, the colons were removed aseptically and homogenized, and serial dilutions were plated to determine CFU counts. Each data point represents the CFU/ml of C. jejuni recovered from the colon of a single mouse. The median for each group is indicated. *, P < 0.05 for the indicated comparison (by ANOVA with Kruskal-Wallis posttest).