(A) Ampicillin-treated mice were challenged with VRE on the fourth day of ampicillin treatment (day -3, green arrow) and administered CBBP or PBS for three consecutive days starting on the third day of VRE colonization (day 0). Fecal pellets were collected at the indicated time points to determine VRE CFUs (top graph). For quantification of total fecal VRE excretion (bottom graph), all fecal pellets per cage were collected and weighed at 24-hour intervals and normalized to the initial time point (day -2). An excretion ratio of 1 indicates no change in the excretion rate (*P = 0.0159, **P = 0.0079, ns = non-significant by the Mann-Whitney test; n = 5 mice per group). (B)
Ex vivo quantification of VRE cultured in fecal suspensions from antibiotic-naïve mice (NT), antibiotic-treated mice, and antibiotic-treated mice colonized with ARM, 7-mix or CBBP (***P = 0.0007, ****P < 0.0001, Mann-Whitney test; n = 5–10 samples per group). (C) VRE growth in cecal content supplemented with cultures of the indicated CBBP strains prior to seeding with VRE (***P < 0.0001, ns = non-significant, Mann-Whitney test with respect to PBS control; n = 12 samples per group). L.o.D., limit of detection; Amp, ampicillin; Cb, C. bolteae; Bp, B. producta; Pd, P. distasonis; Bs, B. sartorii. See also Figures S6 and S7.