rifamycin /rif″ah-mi′sin/ , any of a family of antibiotics biosynthesized from a strain of Streptomyces mediterranei, effective against a broad spectrum of bacteria. The five components are designated A, B, C, D, and E; rifamycins O, S, and SV are derivatives of the B component, and AG and X are derivatives of the O component. It is used for the initial treatment and retreatment of pulmonary tuberculosis and for prevention of meningococcal infections in close contacts of patients with Neisseria meningitidis infections.
