Nontuberculous mycobacteria and the lung: from suspicion to treatment.

Nontuberculous mycobacteria (NTM) are resilient bacteria that grow in virtually any environment, especially those where competing microorganisms are destroyed, such as in chlorinated water. They have been discovered in soil, dust, food, water, and domestic and wild animals. Nontuberculous mycobacteria tend to infect individuals with local (e.g., damaged skin or lung) or systemic (e.g., HIV, drugs, malignancy) defects in host defence, and their incidence and prevalence have consistently increased in the last decade. Difficulty may arise in determining whether an isolated NTM from a microbiological sample is in fact a contaminant or a pathogenic organism. In this review, we discuss the important mycobacteria involved in lung disease, factors that predispose individuals to infection, and their diagnosis and treatment according to updated guidelines. English language publications in MEDLINE and references from relevant articles from January 1, 1990 to June 28, 2009 were reviewed. Keywords searched were "nontuberculous,""mycobacteria," "diagnosis," and "treatment."