Non-tuberculous mycobacteria in patients with non-cystic fibrosis bronchiectasis – a prospective analysis

Background:

The role of non-tuberculous mycobacteria (NTM) in patients with non-cystic fibrosis bronchiectasis (BE) is not yet completely understood, in terms of prevalence, risk factors, prognostic value and other factors.

Methods:

A prospective analysis of a group of patients followed in a specialized BE outpatient clinic was made. Inclusion criteria were: > 18 years old, HRCT scan documented BE, a minimum of 1 year follow-up. Clinical and demographical data were collected, lung function test performed annualy and a sputum bacterial culture was requested at each appointment. Only those with at least two mycobacterial sputum culture were included in this study.

Results:

A total of 140 patients met the inclusion criteria. The mean follow-up time was 3.7 years. A total of 968 mycobacterial sputum cultures were assessed with an average of 2.1 exams per year for each patient. Patients were divided in two groups: bronchiectasis with NTM isolates (n = 23 – 16.4%) and bronchiectasis without NTM isolates (n = 117 – 83.6%). The first group had a higher mean age (59.4 vs. 54.3years), a higher female predominance (78.0% vs. 59.8%) and a lower incidence of tobacco exposure (8.7% vs. 22.2%). No difference was seen in terms of body mass index and prevalence of chest wall or spinal deformities. A higher percentage of chronic bacterial infection (persistence of the same microorganism in 3 sputum samples in 12 months with a minimum interval of one month) was seen in the NTM group (47.8% vs. 37.3%). The most frequent NTM isolates were M. gordonae (n = 7), M. spp. (n = 7) and M. avium (n = 6). In 5 patients the ATS criteria for NTM lung disease were present and treatment was performed.

Conclusions:

A significant percentage of NTM isolates was shown in this bronchiectasis population, due to a routine based screening, although only a small part had NTM lung disease.