Figure 5: C. difficile spore challenge in hamster model studies. Four groups of hamsters (n=6) were gastrically inoculated with 100 c.f.u. of C. difficile (lethal dose) at 2 weeks after the third immunizations of rRBD (0, 3, and 10 μg). The challenge studies are described in the Materials and Methods. Survival rates are recorded.