Demographic risk factors of pulmonary colonization by non-tuberculous mycobacteria

SETTING: British Columbia (BC), Canada. OBJECTIVE: To determine the risk factors for pulmonary colonization by non-tuberculous mycobacteria (NTM). DESIGN: Retrospective study of subjects colonized by NTM from 1990 to 2006. Subjects without mycobacterial disease and with at least three negative cultures served as controls. RESULTS: Mycobacterium avium complex (MAC) species were the most common NTM. Risk factors of colonization included age >= 60 years (aOR 2.3), female sex (aOR 1.2), residency in Canada for at least 10 years (aOR 3.8), Canadian-born aboriginal (aOR 1.8), and Canadian-born non-aboriginal (aOR 1.4). Predictors of MAC colonization included White race (aOR 1.6) and residency in Canada for at least 10 years, which was the strongest predictor (aOR 6.7). Aboriginal origin was associated with non-MAC colonization (aOR 1.8), and Canadian-born people from the East/South-East Asian ethnic groups were protected from MAC colonization (aOR 0.2), all aOR P < 0.05. CONCLUSION: Older age, female sex, having been born in Canada, long residency in BC and White race predict pulmonary NTM colonization, while Aboriginal origin predicts non-MAC colonization. Further research is needed to identify environmental NTM sources in BC and to determine their relation to colonization and disease.