Treatment Outcomes of Mycobacterium avium Complex Pulmonary Disease with a 2-drug Daily Regimen Using Macrolide and...

Limited data exist on the treatment outcomes of a 2-drug daily regimen of macrolide and ethambutol in patients with Mycobacterium avium complex pulmonary disease (MAC-PD).

An outcome analysis was performed on 108 patients with MAC-PD who underwent at least 12 months of treatment with macrolides and ethambutol. Microbiological responses, antibiotic resistance rates, and recurrence rates linked to the regimen were analyzed.

The median overall treatment duration for 108 patients was 13.2 months (interquartile range 12.1-14.6 months). A total of 72 (67%) patients achieved culture conversion and microbiological cure, with a median time to culture conversion of 1.7 months (interquartile range 1.2-4.0 months). A clinical cure was observed in 11 patients; thus, 83 (77%) patients demonstrated a favorable overall response. In the multivariate analysis models adjusted for important clinical variables, no clinical factors were significantly associated with culture conversion. Among patients who failed to achieve culture conversion, macrolide resistance developed in 2 of 18 patients (11%) who had both pre- and posttreatment isolates available. In 2 other patients who failed culture conversion, the minimum inhibitory concentration for ethambutol in the posttreatment isolates increased to ≥8 μg/mL, which was considered resistant. Of the 72 patients who achieved a microbiological cure, 16 (22%) experienced recurrence during follow-up.

The 2-drug daily regimen of macrolides and ethambutol showed moderate efficacy in treating MAC-PD when used for >12 months. However, macrolide resistance occurred in some refractory cases, and recurrence was noted even after successful treatment, highlighting the need for close follow-up.