Effective Treatment for Clarithromycin-resistant Mycobacterium Avium Complex Lung Disease

Clinical management of macrolide-resistant Mycobacterium avium complex (MR-MAC) lung disease is difficult. To date, there only exist a limited number of reports on the treatment of clarithromycin-resistant MAC (CR-MAC) lung disease. This study aimed to evaluate prognostic factors and identify effective treatments in CR-MAC lung disease. We retrospectively collected clinical data of patients newly diagnosed with CR-MAC lung disease at the Kinki-Chuo Chest Medical Center between August 2010 and June 2018. Altogether, 37 patients with CR-MAC lung disease were enrolled. The median age was 69 years; 30, 22, and 21 patients received clarithromycin, ethambutol, and rifampicin, respectively, on their own or in drug combination. The observed sputum culture conversion rate was 29.7% (11/37 patients). In univariate analysis, ethambutol significantly increased the rate of sputum culture conversion (p = 0.027, odds ratio (OR) 10; 95% confidence interval (CI) 1.11-89.77). Multivariate analysis confirmed that ethambutol increased sputum culture conversion rate (p = 0.026; OR 21.8; 95% CI 1.45-329) while the existence of lung cavities decreased it (p = 0.04; OR 0.088; 95% CI 0.009-0.887). The combined use of ethambutol with other drugs may improve sputum culture conversion rate in CR-MAC lung disease.