Treatment of Mycobacterium avium complex bacteremia in AIDS with a four-drug oral regimen. Rifampin, ethambutol, clofazimine, and ciprofloxacin. The California Collaborative Treatment Group.

To determine the quantitative microbiologic response and the clinical response of patients with Mycobacterium avium complex bacteremia and AIDS to an oral antimycobacterial regimen. A phase II, multicenter clinical trial. Four university-affiliated medical centers. Forty-one patients with HIV infection who had at least two consecutive blood cultures positive for M. avium complex and who had not received previous antimycobacterial therapy were enrolled in the study. Thirty-one patients were evaluable with regard to the efficacy of the oral regimen. Patients received a combination of orally administered rifampin (600 mg), ethambutol (15 mg/kg body weight), clofazimine (100 mg once daily), and ciprofloxacin (750 mg twice daily) for 12 weeks. Parenterally administered amikacin, 7.5 mg/kg daily for 4 weeks after the first 4 weeks of oral therapy, was used at the discretion of the individual investigator. Clinical symptoms, Karnofsky scores, and adverse events were monitored. Colony counts for M. avium complex were determined. The mean logarithmic (log) baseline colony count decreased from 2.1 to 0.7 after 4 weeks of oral therapy (P less than 0.001). Suppression of bacteremia was sustained throughout therapy. Thirteen patients (42%) became culture negative during therapy. The mean duration of treatment was 9.7 weeks. Nineteen evaluable patients (61%) completed 12 weeks of therapy. Adverse reactions to one or more agents were common. A rapid reduction in symptoms and bacteremia can be achieved as early as week 2 of therapy using an oral regimen of rifampin, ethambutol, clofazimine, and ciprofloxacin. Colony counts rose dramatically after therapy was discontinued, suggesting that more prolonged periods of therapy are necessary to eradicate systemic infection.