According to the ATS guidelines for diagnosis, treatment and prevention of NTM [2]; pathogenesis of NTM infections is different between patients infected with HIV and patients uninfected with HIV. In HIV infected, NTM infections occurred only when the CD4 T-lymphocyte number falls below 50/µl, suggesting that specific bio-molecules secreted by T-cell are required for resistance against mycobacteria. However, in HIV-uninfected cases, NTM infections are associated with specific mutations in interferon (IFN)-γ and interleukin (IL)-12 synthesis and signalling pathways (e.g. IFN-receptor 1 [IFNR1], IFN- receptor 2 [IFNR2], IL-12 receptor 1 subunit [IL12R1], the IL-12 subunit p40 receptor 1 [IFNR1], IFN- receptor 2 [IFNR2], IL-12 receptor 1 subunit [IL12R1], the IL-12 subunit p40 [IL12p40], the signal transducer and activator of transcription 1 [STAT1], and the nuclear factor- essential modulator [NEMO] ). Exact mechanism of NTM pathogenesis has not been discovered. Various NTM species are known to have varying virulence capabilities.

Recently, there has been a rapid increase in the isolation of NTM predominantly due to an increase in the immunocompromised population and also due to the availability of more accurate identification techniques and greater disease awareness. Diagnosis of NTM infections is challenging due to overlap of clinical manifestations of NTM diseases with TB [3]. Over past few decades the diagnosis of NTM infections was based on the clinical features, associated risk factors and antibiogram patterns [4, 5]. Diagnosis and drug susceptibility testing of NTM is of great significance in the management owing to the fact that NTM are relatively resistant to most of the first- and second-line drugs used for the treatment of TB. This property, sometimes leads to misidentification of NTM as MDR-TB [6]. Recent epidemiological data suggest a worldwide increase in both incidence as well as prevalence of NTM disease. NTM are increasingly recognized to cause both pulmonary and extra-pulmonary diseases. Evidence also points towards a change in the epidemiology of NTM diseases and its occurrence both in immunocompetent as well as immunocompromized populations [7]. Pre-existing lung diseases and age more than 50 years are known risk factors, and reports from non European countries have documented its occurrence even in non-smoker females without pre-existing diseases.