Wiesława Lewgowd, Anna Ferra, Andrzej Stańczak
Ansamycins. They are a family of antibiotics including rifamycin, rifampicin, rifambutin and rifapentin. Rifampicin, rifambutin and rifapentin are semi-synthetic antibiotics, derived from rifamycin. The rifamycins are a group of antibiotics synthesized either naturally by the bacterium Streptomyces mediterranei or artificially. They are particularly effective against mycobacteria and are therefore used to treat tuberculosis, leprosy, and mycobacterium-avium-complex (MAC) infections. The antibiotic affects mainly Gram-positive bacteria. Gram-negative bacteria are much less sensitive to them. Rifamycinis bactericidal effect is caused by the inhibition of RNA synthesis in bacteria. The antibiotic interacts with RNA polymerase, thus inhibiting the synthesis for long RNA strands. Rifamycin and its derivatives have assumed importance because of its superior in vivo activity against mycobacterial tuberculosis, making it very effective in the treatment of this dreaded disease.