Mapping the Footprints of Nontuberculous Mycobacteria: A Diagnostic Dilemma

Abstract NTM are widely distributed in nature and have been isolated from soil, natural water, tap water, water used in showers and surgical solutions. Although Mycobacterium tuberculosis is by far the most important mycobacterial species from a public health perspective, other species of nontuberculous mycobacteria (NTM) are being encountered with increasing frequency and new species are being identified. While not all NTM are pathogenic for humans, many are. Pathogenic NTM are usually less virulent than M. tuberculosis , and potential pathogens may be isolated without obvious association with a disease. On the contrary, species usually considered benign, may produce disease especially in immune-compromised individuals. The prevalence of NTM among world population has significant geographic variation that might occur even within the same country. Because of the large number of potentially pathogenic NTM that can be encountered in the clinical laboratory, diagnosis of these organisms is required to ensure appropriate treatment. However, diagnosis of NTM infection is often difficult. Bacteriological, radiological and clinical criteria to diagnose a disease are often not able to discriminate between M. tuberculosis and NTM infection. Moreover, a positive tuberculin skin test, does not allow distinction between NTM and M. tuberculosis infection. Since, labour intensive conventional methods of speciation are not used in every laboratory, NTM infections go unreported and are thus ignored. A greater laboratorian-clinician coordination would greatly benefit the recognition and treatment of these potential pathogens.