Rifabutin is primarily bactericidal antibiotic drug used to treat tuberculosis. Its effect on bacteria is based on the DNA-dependent RNA polymerase blocking drug rifamycin S., a semi-synthetic derivative. It is effective, for example, in highly resistant mycobacteria, Gram-positive bacteria (and some are effective against Gram-negative bacteria), but also against Mycobacterium tuberculosis, M. leprae, and M. avium intracellulare.
Rifabutin is an antibiotic; antitumor. Rifabutin interferes with HSP-90 molecular chaperone, enhances ubiquitination and protein degradation, and inactivates bacterial RNA polymerase.