Molecular Identification of Non-tuberculous Mycobacteria in Suspected Tuberculosis Cases in Central India

Introduction Mycobacterium tuberculosis complex (MTBC), the primary cause of tuberculosis (TB), must be accurately identified to implement effective patient management and control strategies. Non-tuberculous mycobacteria (NTM) in suspected TB cases can result in erroneous diagnoses and needless treatment. Objective The study aimed to identify NTM in patients suspected of TB at a tertiary care hospital in central India using molecular methods. Methods This prospective study enrolled 400 suspected pulmonary and extra-pulmonary TB patients. Patients between the age of two to 90 years, of either gender, new and previously treated cases, Culture positive, patients with immune-compromised status, patients not responding to ATT, HIV positive and negative, and willing to give consent were included in the study. Liquid culture via the Mycobacterial growth indicator tube (MGIT) system was used to culture mycobacteria from clinical samples. The SD Bioline Ag MPT64 Test (Standard Diagnostics, South Korea) and in-house multiplex-PCR (mPCR) were used to differentiate between Mycobacterium tuberculosis complex and NTM species for the molecular identification of NTM GenoType® Mycobacterium Common Mycobacteria (CM) assay kit (HAIN Life Science, Nehren, Germany) was used following the manufacturer's protocol. Results Only 59/400 (14.7%) of the samples produced a positive result in MGIT culture, indicating the presence of mycobacteria, and 85.25% of the remaining 341 samples were negative for mycobacterial growth. Further investigation of these 59 cultures with mPCR and SD Bioline Ag MPT64 test showed that 12 (20.33%) cultures were determined to be NTM, while the remaining 47 (79.67%) were identified as MTBC. Genotype characterization with GenoType® mycobacterium CM assay kit revealed that five of the 12 NTM isolates (41.67%) showed patterns that were consistent with Mycobacterium (M.) fortuitum, three (25%) showed patterns that were consistent with M. abscessus, and four (33.33%) showed patterns that were consistent with M. tuberculosis. Conclusion These results emphasize the value of molecular methods for precisely identifying mycobacterial species, particularly in suspected TB cases. The high prevalence of NTM in positive cultures emphasizes the significance of differentiating between MTBC and NTM to prevent misdiagnosis and ensure proper care. Understanding the epidemiology and clinical significance of these organisms in central India is made possible by the identification of particular NTM species.