A randomized, placebo-controlled study of rifabutin added to a regimen of clarithromycin and ethambutol for treatment of disseminated infection with Mycobacterium avium complex

Current guidelines suggest that disseminated Mycobacterium avium complex (M AC) infection be treated with a macrolide plus ethambutol or rifabutin or b oth. From 1993 to 1996, 198 AIDS patients with MAC bacteremia participated in a prospective, placebo-controlled trial of clarithromycin (500 mg b.i.d. ) plus ethambutol (1,200 mg/d), with or without rifabutin (300 mg/d). At 16 weeks, 63% of patients in the rifabutin group and 61% in the placebo group (P = .81) had responded bacteriologically. Changes in clinical symptoms an d time to survival were similar in both groups. Development of clarithromyc in resistance during therapy was similar in the two groups; of patients who had a bacteriologic response, however, only 1 of 44 (2%) receiving rifabut in developed clarithromycin resistance, vs. 6 of 42 (14%) in the placebo gr oup (P = .055), Thus, rifabutin had no impact on bacteriologic response or survival but may protect against development of clarithromycin resistance i n those who respond to therapy.