[Nontuberculous mycobacteria: clinically relevant].

The nontuberculous or atypical mycobacteria (NTM) are a group of largely opportunistic pathogens, which are increasingly being detected in patients and being associated with clinical disease. Various host factors are responsible for this, such as the ageing population with the accompanying increase in the number of patients with chronic diseases, but NTM are also detected more often as a result of improvements in diagnostic laboratory techniques. The clinical relevance, i.e. the percentage of patients in whom the detected NTM is actually the cause of the clinical disease, differs enormously per species. Pulmonary NTM disease, which resembles pulmonary tuberculosis, is the most frequent, followed by lymphadenitis in children. Treatment of these infections is time-consuming, complicated and often ineffective. Therefore, prompt consultation with one of the specialized centres of expertise is warranted. We should also consider formulating national guidelines for diagnosis and treatment.