Efficacy of Fluoroquinolones as Substitutes for Ethambutol or Rifampin in the Treatment of Mycobacterium avium Complex Pulmonary Disease According to Radiologic Types.

During the treatment of Mycobacterium avium complex pulmonary disease (MAC-PD), ethambutol or rifampin is often discontinued because of adverse events. This study investigated the treatment outcomes when broader-spectrum fluoroquinolones replace ethambutol or rifampin in MAC-PD treatment based on the radiologic type. From 2006 to 2019, patients who initiated standard treatment and whose treatment duration was ≥1 year were retrospectively identified at a tertiary referral center in South Korea, including 178 patients with cavitary disease (fibrocavitary and cavitary nodular bronchiectatic types) and 256 patients with the noncavitary nodular bronchiectatic (NC-NB) type. We compared the microbiologic cure at 1 year between the patients who maintained the initial regimen and those who replaced ethambutol or rifampin with fluoroquinolones (moxifloxacin or levofloxacin). The overall microbiologic cure rate of the 178 patients with cavitary disease was 71.3%. Among these, the microbiologic cure rates of the 16 patients who substituted fluoroquinolones for ethambutol were lower than those of the 156 patients who maintained three-drug oral antibiotics with aminoglycoside (37.5% versus 74.4%, respectively; P = 0.007), which was statistically significant in multivariate analysis. The outcomes of the six patients receiving fluoroquinolones as an alternative to rifampin were similar to that of those continuing the initial regimen. The microbiologic cure rate of the patients with the NC-NB type receiving daily or intermittent oral three-drug therapy was similar regardless of maintaining the initial therapy or replacing ethambutol or rifampin with fluoroquinolones. In conclusion, in cavitary MAC-PD, replacing ethambutol with fluoroquinolones resulted in inferior patient outcomes.