Percentage loss of spore optical density after incubation of C. difficile spores with bile salts for 2 h.

C. difficile spores were heat treated at 60°C for 25 min and then incubated with either i) BHIS supplemented with 0.1% (w/v) taurocholate; ii) BHIS supplemented with 0.1% (w/v) taurocholate and 2 mM chenodeoxycholate; or iii) BHIS alone. The data represent the average of three independent experiment and numbers in parentheses represent the mean of the final OD600 value.