Clinical efficacy of sitafloxacin-containing regimens for Mycobacterium avium complex pulmonary disease.

BACKGROUND: Fluoroquinolones (FQ) have shown efficacy against Mycobacterium avium complex (MAC) across experimental settings, in vitro and in vivo. Sitafloxacin (STFX) has demonstrated particularly strong anti-MAC activity, but clinical data on its effectiveness in treating MAC pulmonary disease (MAC-PD) are sparse. This study aimed to evaluate the efficacy of STFX-containing regimens in patients with MAC-PD. METHODS: This retrospective cohort study included 50 patients with MAC-PD who received STFX-containing regimens for ≥6 months at a single center between January 2015 and March 2024. Patients were categorized into four groups: Group 1, STFX-treated without surgery (n = 49); Group 2, STFX started ≥6 months after guideline-based treatment (GBT) began (n = 40); Group 3, poor radiologic response to GBT (n = 38); and Group 4, persistent positive sputum cultures at STFX initiation (n = 19). Primary outcomes assessed at six months included radiologic improvement using the NICE (Nodule, Infiltration, Cavity, Ectasis) score, sputum culture conversion (defined as ≥2 consecutive negative cultures obtained ≥4 weeks apart), and symptom improvement (using the COPD Assessment Test [CAT] score). RESULTS: Radiologic improvement, symptomatic improvement, and sputum culture conversion were observed in 18.4%, 19.1%, and 20.0% of patients in Group 1; 12.5%, 20.0%, and 12.5% in Group 2; 13.2%, 18.4%, and 13.3% in Group 3; and 5.3%, 15.8%, and 12.5% (2 of 16 evaluable patients) in Group 4, respectively. The two patients who achieved culture conversion had clarithromycin-susceptible strains, non-cavitary disease, and received concomitant ethambutol. CONCLUSIONS: STFX-containing regimens demonstrated modest and overall limited efficacy in patients with MAC-PD, with fewer than 20% achieving radiologic, symptomatic, or microbiological improvement across all groups. STFX may be considered an alternative adjunct when standard therapies are not feasible; however, its overall therapeutic role appears limited.