Rifalazil is a rifamycin derivative, inhibits the bacterial DNA-dependent RNA polymerase and kills bacterial cells by blocking off the beta-subunit in RNA polymerase. Rifalazil is an antibiotic, exhibits high potency against mycobacteria, gram-positive bacteria, Helicobacter pylori, C. pneumoniae and C. trachomatis (MIC: 0.00025 to 0.0025 ug/ml).