Varying concentrations of Turbomycin A (0, 0.5, 1, 5 and 10 μg/ml) or 1-acetyl-β-carboline (0, 1, 5, 10 and 25 μg/ml) and either cholic acid (CA) (0 to 100 μM), deoxycholic acid (DCA), (0 to 100 μM) or lithocholic acid (LCA), (0 to 25 μM) were added to PYF medium, inoculated with 106 vegetative cells/ml of C. difficile, incubated for 24 hrs. and optical density reading determined at 600 nm. * p< 0.05, ** p< 0.01