About The Study

This study compared two multi-drug treatments for Mycobacterium avium complex (MAC) bacteria in HIV-infected adults.

Study Approach

This was a phase III study that measured how well two different treatments work in large groups of people. Participants were randomly assigned to one of two groups: 1- rifampin (600 mg daily), ethambutol (15 mg/kg daily), ciprofloxacin (750 mg twice daily) and clofazamine (100 mg daily); or 2- clarithromycin (1 gm twice daily), ethambutol (15 mg/kg daily) and rifabutin (300 mg daily).

Study population

Two hundred and twenty-nine participants were enrolled in 23 Canadian sites.


The rate of eliminating MAC from the bloodstream was significantly greater in the three-drug arm than in the four-drug arm (69% vs 29%). Survival was also significantly longer in the three-drug arm (median survival 8.6 months vs 5.2 months). The rifabutin dose was changed from 600 mg daily to 300 mg daily mid-trial because uveitis (an eye inflammation) occurred in 24 of 63 patients. The superiority of the three-drug arm over the four-drug arm in improving survival was the same in both doses of rifabutin. The rate of eliminating MAC itself was less with the low dose of rifabutin, but still remained significantly better in the three-drug arm.


The three-drug combination of clarithromycin, ethambutol and rifabutin is significantly better than the four-drug combination of rifampin, ethambutol, ciprofloxacin and clofazimine in eliminating MAC bacteria from the bloodstream and improving survival of people living with AIDS.