Oral Macrolide Therapy Following Short-term Combination Antibiotic Treatment of Mycobacterium massiliense Lung Disease

BACKGROUND: Although Mycobacterium massiliense lung disease is increasing in patients with cystic fibrosis and non-cystic fibrosis bronchiectasis, optimal treatment regimens remain largely unknown. This study aimed to evaluate the efficacy of oral macrolide therapy after an initial 2-week course of combination antibiotics for the treatment of M massiliense lung disease. METHODS: Seventy-one patients received oral macrolides, along with an initial 4-week (n = 28) or 2-week (n = 43) IV amikacin and cefoxitin (or imipenem) treatment. These patients were treated for 24 months (4-week IV group) or for at least 12 months after negative sputum culture conversion (2-week IV group). RESULTS: Total treatment duration was longer in the 4-week IV group (median, 23.9 months) than in the 2-week IV group (15.2 months; P < .001). The response rates after 12 months of treatment were 89% for symptoms, 79% for CT scanning, and 100% for negative sputum culture results in the 4-week IV group. In the 2-week IV group, these values were 100% (P =.057), 91% (P =.177), and 91% (P =.147), respectively. Acquired macrolide resistance developed in two patients in the 2-week IV group. Genotyping analyses of isolates from patients who did not achieve negative sputum culture conversion during treatment and from those with positive culture results after successful treatment completion revealed that most episodes were due to reinfection with different genotypes of M massiliense. CONCLUSIONS: Oral macrolide therapy after an initial 2-week course of combination antibiotics might be effective in most patients with M massiliense lung disease.