Activities of tizoxanide and nitazoxanide compared to those of five other thiazolides and three other agents against anaerobic species.

Agar dilution was used, and MICs of metronidazole, tizoxanide, nitazoxanide, denitrotizoxanide, RM 4803, RM 4807, RM 4809, RM 4819, amoxicillin-clavulanate, and clindamycin were measured against 412 anaerobes. Nitazoxanide, tizoxanide, RM 4807, and RM 4809 were active against all groups, except for gram-positive non-spore-forming rods with 50% minimum inhibitory concentrations (when the latter were excluded) of 1 to 2 microg/ml and 90% minimum inhibitory concentrations of 4 to 8 microg/ml, respectively. Metronidazole MICs were usually lower against all groups except clostridia.