Objective: To determine the antimicrobial activity and tolerability of clarithromycin for treating bacteremic Mycobacterium avium complex disease in patients with the acquired immunodeficiency syndrome (AIDS).
Design: A randomized, double-blind, dose-ranging study.
Setting: Outpatient clinics.
Patients: 154 patients with human immunodeficiency virus (HIV) infection and blood cultures positive for M. avium complex who had symptomatic disease.
Interventions: Random assignment to clarithromycin at dosages of 500 mg, 1000 mg, or 2000 mg twice daily for 12 weeks.
Main outcome measure: Median number of colony-forming units of M. avium complex per milliliter of blood.
Results: Clarithromycin decreased mycobacterial CFUs from 2.7 to 2.8 log 10/mL of blood at baseline to less than 0 log 10/mL during follow-up (P < 0.0001). After 2 weeks, patients receiving 500 mg twice daily were less likely to be culture negative than were patients receiving 1000 or 2000 mg twice daily (11% compared with 33% or 29%; P = 0.08). At 6 weeks, the median number of CFUs of M. avium complex/mL of blood was 0 or 1 for all three groups. Clarithromycin-resistant isolates of M. avium complex developed in 46% of patients at a median of 16 weeks. Median survival was longer in patients assigned to 500 mg twice daily (median, 249 days) than in patients assigned to 1000 mg or 2000 mg. Death in the first 12 weeks was lowest in the 500-mg group (P = 0.007).
Conclusions: Clarithromycin therapy acutely decreased M. avium complex bacteremia in patients with HIV infection by more than 99%. Clarithromycin, 500 mg twice daily, was well tolerated and associated with better survival. Emergence of clarithromycin-resistant organisms was an important problem.