Experimental design of the study. Mice were administered a mixture of antibiotics every 12 h for 2 weeks (in green; wks, −2÷ 0). Animals were sacrificed at the end of the antibiotic treatment (abx) or 2, 4, or 6 weeks post antibiotic discontinuation (in orange; wash-out, w/o). Control animals (in blue; vehicle) received the same volume of the vehicle for the same period; since data obtained from the control animals at the different time points are comparable, the results of the controls are organized and reported as a single animal control group. Asterisks indicate the time of collection of the cecal content and the time of the sacrifice. Abbreviations: wks, weeks; abx, antibiotics; w/0, wash-out. * denotes sacrifice of the animals.