FIG 4.

Effect of thioglycolic acid on stimulation of germination of C. difficile spores. Spores (10⁶ CFU) were incubated at 22°C for 1 h in sterile water versus sterile water supplemented with 1 mg/ml thioglycolic acid alone or in combination with 1 mg/ml lysozyme and at pH 5 and 7.6, and aliquots were subjected to heat shock at 80°C for 5 min to determine the log reductions (as activated spores are killed at 80°C, whereas nongerminated spores are not). Error bars indicate standard errors.