3. Female participants of childbearing potential not willing to use one of the following methods of birth control for the duration of the study and 90 days after study completion: condoms, sponge, foams, jellies, diaphragm, non-hormonal intrauterine device, a vasectomized sole partner or abstinence. Note: Oral contraceptive pills are not effective birth control when taking rifamycin. A negative urine pregnancy test at screening visit if female of childbearing potential