FIG 6.

Effects of oligopeptide transporters on fecal spore output and virulence in the hamster model of CDI. (A) Total number of C. difficile spores per gram of feces recovered at 24 h postinfection from two independent experiments of clindamycin-treated Syrian golden hamsters inoculated with 500 spores of C. difficile 630Δerm, MC296 (opp), MC301 (app), or MC307 (opp app). Fecal samples were weighed, resuspended in 1× PBS, and plated onto TCCFA plates (95, 96), and C. difficile colonies were enumerated after 48 h. Solid lines, the median for each strain; dotted line, limit of detection (4.51 × 10³ CFU/g). (B) Kaplan-Meier survival curve representing the cumulative results from the same two independent experiments described in the legend to panel A. Hamsters infected with the mutant strains succumbed more rapidly than those infected with the parent strain. Mean times to morbidity were as follows: 630Δerm, 45.1 ± 6.4 h; MC296 (opp), 38.4 ± 6.6 h; MC301 (app), 38.2 ± 5.8 h; and MC307 (opp app), 35.0 ± 4.9 h (P < 0.02 for all mutants, log rank test).