ABSTRACT
PURPOSE: The optimal treatment regimen for Mycobacterium avium complex (MAC) lung disease has not yet been fully established. We evaluated the efficacy of standardized combination antibiotic therapy and the factors that might affect unfavorable microbiologic responses in patients with MAC pulmonary disease. MATERIALS AND METHODS: This retrospective study reviewed data from 96 patients (56 females; median age 59 years) treated with newly diagnosed MAC lung disease between January 2003 and December 2006. RESULTS: All patients received standardized combination antibiotic therapy, consisting of clarithromycin, rifampicin, and ethambutol. Streptomycin was additionally given in 72 patients (75%) for a median duration of 4.5 months. The overall favorable microbiologic response rate was 79% (76/96); 20 patients (21%) had unfavorable microbiologic responses, including failure to sputum conversion (n = 13), relapse (n = 3), and MAC-related death (n = 4). A positive sputum acid-fast bacillus smear at the start of treatment was an independent predictor of an unfavorable microbiologic response. CONCLUSION: Standardized combination antibiotic therapy consisting of clarithromycin, rifampicin, and ethambutol with or without initial use of streptomycin is effective in treating patients with newly diagnosed MAC lung disease.