FIG 2.

Vegetative C. difficile persists in the HIO lumen. (A) HIOs injected with either C. difficile strain VPI 10463 or F200 were collected at 0, 2, and 12 h postinjection and plated on BHI with cysteine to quantitate the number of vegetative CFU per HIO. C. difficile was able to persist in the lumen of HIOs for 12 h. Points on the graph represent individual HIOs, and the dashed line represents the limit of detection. Bars indicate the means and SEM. (B) Twelve hours after colonization, HIOs injected with C. difficile were fixed and stained using hematoxylin and eosin. The epithelium of the HIO colonized with strain VPI 10463 is severely disrupted, and large rods with what appear to be subterminal spores are visible (inset) within the HIO (inset is a 3.25× digital zoom of the boxed region). (C) An HIO colonized with the nontoxigenic strain F200 has an intact epithelium despite the presence of large rod-shaped bacteria in the lumen of the HIO.