Diagnosing nontuberculous mycobacterial lung disease - A process in evolution

The nontuberculous mycobacteria (NTM) were recognized widely as human pathogens only relatively recently. Defining diagnostic criteria for these organisms has been difficult because of the wide range of virulence among NTM species and the sometimes very indolent diseases that they produce. These two factors have led to the description of many NTM respiratory isolates as airway colonizers, further complicating interpretation of their clinical significance. There is now a better appreciation for the spectrum of disease caused by NTM, and recent diagnostic guidelines for NTM disease take into account the sometimes very slowly progressive nature of NTM disease. Still, no set of diagnostic guidelines can be adequate for the entire genus Mycobacterium, so that diagnostic evaluation of NTM isolates (especially respiratory isolates) will continue to evolve.