FIG 3.

Injection of toxigenic but not nontoxigenic C. difficile results in loss of HIO barrier function. (A) HIOs were injected with FD4 alone (control) (n = 5), a nontoxigenic strain (F200) of C. difficile (n = 5), filtered culture supernatant from that strain (n = 6), a toxigenic C. difficile strain (VPI 10463) (n = 5), or filtered culture supernatant from the toxigenic strain (n = 5). Only VPI 10463-injected HIOs lost barrier function. Images are representative of three independent experiments using 5 to 6 HIOs per group. (B) Quantification of epithelial barrier disruption by measuring retention of injected FD4 after 12 h. Bars represent the medians and the interquartile ranges. Only the HIOs colonized with the toxigenic strain (VPI 10463) lost a significantly greater amount of FD4 from the lumen, indicating significant epithelial damage (P = 0.0079 by Mann-Whitney test).