... of respiratory diseases Introduction:Several semisynthetic derivatives (rifamycin SV, rifampin [rifampicin], rifamide) of natural rifamycins have been used as ... against several viruses. Fungal and yeast infections resistant to rifampin alone often respond when a rifamycin is added to ... an antifungal agent (eg, amphotericin B). Rifampin has been used in foals to control pneumonia induced by ...