When and how to treat pulmonary non-tuberculous mycobacterial diseases.

Non-tuberculous mycobacteria are ubiquitous environmental organisms that have been recognized as a cause of pulmonary infection for over 50 years. Traditionally patients have had underlying risk factors for development of disease; however, the proportion of apparently immunocompetent patients involved appears to be rising. Not all patients culture-positive for mycobacteria will have progressive disease, making the diagnosis difficult, though criteria to aid in this process are available. The two main forms of disease are cavitary disease (usually involving the upper lobes) and fibronodular bronchiectasis (predominantly middle and lingular lobes). For patients with disease, combination antibiotic therapy for 12-24 months is generally required for successful treatment, and this may be accompanied by drug intolerances and side-effects. Published success rates range from 30% to 82%. As the progression of disease is variable, for some patients, attention to pulmonary hygiene and underlying diseases without immediate antimycobacterial therapy may be more appropriate. Surgery can be a useful adjunct, though is associated with risks. Randomized controlled trials in well-described patients would provide stronger evidence-based data to guide therapy of non-tuberculous mycobacteria lung diseases, and thus are much needed.