rifamycin
/rɪfəˈmʌɪsɪn/(also rifomycin) Pharmacology
noun
Any of a group of natural and semi-synthetic antibiotics originally isolated from the actinomycete Nocardia mediterranei, which inhibit microbial DNA-dependent RNA synthesis and have a bactericidal action, especially on mycobacteria and Gram-positive bacteria.
Origin
1950s. Probably from rifo- + -mycin. Compare Italian rifomicina.