Mycobacterium abscessus complex is the second most common organism isolated from patients with nontuberculous mycobacterial (NTM) lung disease in South Korea. This study aimed to compare clinical features and treatment outcomes of M. abscessus and Mycobacterium massiliense lung disease.

We retrospectively identified stored clinical isolates of M. abscessus complex as either M. abscessus or M. massiliense and reviewed medical records to compare clinical characteristics and treatment responses. All patients were treated empirically over several months with multidrug regimens, including a macrolide and one or more parenteral agents.

Of the 249 patient isolates tested, 128 (59 with M. abscessus and 69 with M. massiliense) met the American Thoracic Society diagnostic criteria for NTM pulmonary disease, and treatment outcomes were analyzed in 48 patients (26 with M. abscessus and 22 with M. massiliense). The clinical and radiologic findings were similar between the two groups. Although the durations of parenteral and total treatment were significantly shorter in patients with M. massiliense than in those with M. abscessus (4.7 months vs 7.4 months, P = .006, and 12.1 months vs 16.3 months, P = .043), the treatment success rate was significantly higher in patients with M. massiliense (95.5%) than in M. abscessus cases (42.3%, P < .001).

Patients with M. massiliense pulmonary infection responded better to this antibiotic strategy than those with M. abscessus infection. A shortened duration of treatment may be sufficient for M. massiliense pulmonary infection.