Fig. 1

Mice infected with epidemic ribotype isolates had lower survival than mice infected with non-epidemic ribotype isolates. For each isolate, groups (n = 20) were housed 5 to a cage and inoculated with approximately 1 × 10⁶ C. difficile spores. a The non-epidemic ribotype isolates are denoted by black survival curves, and the epidemic ribotypes are denoted by gray. Survival was monitored for 12 days, and there were no additional deaths for any isolate after day 7. b Percent survival at 12 days after infection. An asterisk denotes significant difference at p ≤ 0.05 (Student’s unpaired t test)