BACKGROUND The long-term treatment outcomes of Mycobacterium avium complex (MAC) lung disease (LD) have not been adequately evaluated.

OBJECTIVE We evaluated the determinants of microbiological recurrence after successful treatment for MAC LD.

DESIGN The medical records of 295 MAC LD patients treated with combination chemotherapy from 2004 to 2013 were reviewed. The clinical data, microbiological study results and chest computerised tomography findings were collected for each patient.

RESULTS Ninety-one patients who maintained negative sputum conversion during treatment and had a minimum 10-month follow-up period after treatment were included. The median duration of follow-up was 25 months. Seventy-one (78.0%) patients remained microbiologically disease-free, while 20 (22.0%) had microbiological recurrence after successful treatment. Age, sex and body mass index were not associated with microbiological recurrence. Longer intervals between initial diagnosis and administration of medication (P = 0.024), increased number of involved lobes (P = 0.033) and failure of sputum conversion within 6 months of initiating treatment (P = 0.017) were significantly associated with microbiological recurrence.

CONCLUSION Microbiological recurrence after successful anti-MAC chemotherapy was associated with the time interval between initial diagnosis and administration of medication, number of lobes involved and time to sputum conversion during treatment.