Profile of patients with pulmonary non-tuberculous mycobacterial disease mimicking pulmonary tuberculosis

Abstract Introduction With the introduction of newer molecular diagnostic tools, an increasing number of Non-tuberculous Mycobacteria (NTM) affecting the respiratory system and mimicking symptoms of pulmonary tuberculosis (PTB) are being identified. They may be misdiagnosed and treated as PTB, often categorized as treatment failures if they do not respond to treatment. This manuscript aims to characterize patients with pulmonary NTM disease. Methods Patient characteristics of bacteriologically confirmed pulmonary NTM disease, attending the ICMR-National Institute for Research in Tuberculosis, Chennai were prospectively compiled over a two-year period (2017–2018). Results A total of 122 patients with recurrent chest symptoms and not responding to anti-tuberculosis treatment were screened for NTM. Thirty-nine cases (26 males and 13 females) of symptomatic pulmonary NTM were diagnosed. The mean (SD) patient age and body mass index were 48.6 ± 11 years and 16.3 ± 3. All male participants were smokers, had at least one episode of previous ATT. Mycobacterium kansasii (48.7%) was the most frequently isolated species followed by Mycobacterium intracellulare (20.5%), Mycobacterium abscessus (7.6%) followed by Mycobacterium avium, Mycobacterium fortuitum, Mycobacterium kyorinense, and Mycobacterium simiae . Infection with multiple NTMs was seen in four patients. Isoniazid resistance was identified in 20 patients. Based on species identified, treatment was initiated as per American Thoracic Society guidelines and continued up to 12 months of culture negativity. Conclusions M. kansasii is the commonest pulmonary NTM isolated in Tamilnadu with a higher prevalence in males and elderly. Sensitization of both patients and providers is essential to avoid misdiagnosis and delay in diagnosis of pulmonary NTM disease as pulmonary TB.