Computed tomographic findings of macrolide-resistant Mycobacterium massiliense pulmonary disease and changes after antibiotic treatment

The purpose of this study was to present the computed tomographic (CT) findings of lung abnormalities in macrolide-resistant Mycobacterium massiliense pulmonary disease and its changes in follow-up CT after antibiotic treatment. Chest CT scans of patients with macrolide-resistant M massiliense pulmonary disease (n = 19) were retrospectively reviewed. Patients were treated with multidrug therapy, and sputum examinations were performed. Follow-up CT scans obtained during antibiotic treatment after detection of macrolide resistance were also reviewed, if available (n = 13). The CT scores at detection of macrolide resistance and at the last follow-up periods were also compared. Of all patients with macrolide-resistant M massiliense pulmonary disease, 2 (11%) patients achieved sputum culture conversion during the follow-up period. The most common CT findings of M massiliense pulmonary disease at detection of macrolide resistance were bronchiectasis and bronchiolitis (n = 19, 100%), followed by consolidation (n = 16, 84%), cavities (n = 11, 58%), and nodules (n = 6, 32%). On the last follow-up CT, overall CT scores were increased in 8 (62%) of 13 patients, and total mean CT score was significantly increased (P = .021). For each CT pattern, the cavity showed the greatest increase in CT score (P = .027), followed by bronchiectasis (P = .038). Common CT findings of macrolide-resistant M massiliense pulmonary disease were similar to those of pulmonary disease caused by other species of nontuberculous mycobacteria at presentation. However, in macrolide-resistant M massiliense pulmonary disease, serial CT scans showed deterioration with cavitary and bronchiectatic change in most patients despite multidrug antibiotic therapy.