A daily triple-drug regimen containing clarithromycin, rifampin and ethambutol for the treatment of nodular/bronchiectatic mycobacterium avium complex (MAC) lung disease produces a relatively high response rate similar to that seen in previous reports, as shown in a retrospective study from Japan.

However, there appears to be an increased frequency of recurrence after treatment, suggesting that the regimen may be insufficient even in mild nodular/bronchiectatic disease, according to the investigators. “A long-term maintenance treatment would be needed in some patients with mild MAC lung disease.”

In the study, the investigators looked at 34 nodular/bronchiectatic MAC lung disease patients (median age 61 years; 73.5 percent female) who were treated with the triple-drug regimen for a median duration of 18.5 months. Patients received clarithromycin, rifampin and ethambutol at median doses of 800, 450 and 500 mg/day, respectively. The median follow-up time was 92.3 months. [APSR 2017, abstract AP303]

There were 31 patients (91.2 percent) who showed symptom reductions, while 29 (85.3 percent) achieved radiological improvement. For 24 patients (70.6 percent), sputum culture results were converted from positive to negative.

Despite the favourable results, five patients (14.7 percent) continued their treatment for a long time because of disease instability. Sixteen patients (47.1 percent) had a relapse, showing a clinical or radiological worsening in a median of 17.9 months after treatment, and 12 (35.3 percent) of them restarted treatment. Overall, only 13 patients (38.2 percent) achieved long-term disease stability.

Currently, macrolides (clarithromycin and azithromycin) are the cornerstones of treatment for MAC lung disease. The recommended treatment regimen for patients with nodular/bronchiectatic disease includes a rifamycin (rifampin or rifabutin), ethambutol and a macrolide administered intermittently (three times weekly) for 18 to 24 months, with 12 months of sputum culture negativity. [Clin Chest Med 2015;36:55-66; Tuberc Respir Dis (Seoul) 2016;79:74–84]

“Daily administration is recommended as a more intensive treatment for patients with fibrocavitary disease or severe nodular/bronchiectatic disease,” the investigators noted, adding that such a treatment schedule is more common in Japan regardless of disease severity.