Compounds tested as agonists and antagonists of C. difficile spore germination. Taurocholate (compound I), cholate (compound II), taurine (compound III), glycine (compound IV), sodium dodecyl sulfate (SDS; compound V), Triton X-100 (compound VI), N-methylglycine (compound VII), glycine methyl ester (compound VIII), chenodeoxycholate (compound IX), taurochenodeoxycholate (compound X), glycochenodeoxycholate (compound XI), and 7-ketolithocholate (compound XII).