FIG 3.

Gut microbiota is required for drug-mediated protection against CDI. (A) Experimental design of CDI infection in germfree (GF) mice. As no antibiotic pretreatment was required, GF mice were infected with C. difficile spores and administered lead drugs or the vehicle control PBS at the time of infection. (B to D) Survival (B), development of clinical scores (C), and weight loss (D) were monitored over the course of infection. (E) Bacterial burden in the cecal contents was determined at the time of necropsy by qPCR analysis of the quantities of 16S rRNA gene copies of C. difficile relative to the total number of 16S rRNA gene copies in the cecal contents. Expression levels are shown in comparison to the PBS-treated group on a log₁₀ scale. (F and G) Toxin titers were determined in cecal contents collected at the time of necropsy by toxin ELISA. Data are the mean ± SE of the results for 3 to 6 mice/group.