Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 17 6 2025 12 13 936 941 Harisree Sudersanan Department of Microbiology, Government Medical College, Ernakulam, Kerala, India Nikhilesh Menon Ravikumar Department of Health Services, Assistant Surgeon, State Nodal Officer (Lab Network), Govt of Kerala, India Baijayanti Mishra Department of Microbiology, St. John’s Medical College, Bangalore, India 2024 11 28 2025 11 13 Background and Objectives: Tuberculosis (TB) is an infectious disease that is among the most common in the world and is a leading cause of high mortality and morbidity. In India, there is very limited data on second line drug susceptibility testing. The aim of the study was to find out the prevalence of Multi Drug Resistant (MDR) isolates among Mycobacterium tuberculosis (MTB) complex strains and to assess the sensitivity pattern to four commonly used 2nd line anti-tubercular drugs irrespective of their MDR status. Materials and Methods: A 61 culture-positive strains of the tuberculosis complex (smear positive or negative) in Mycobacterium Growth Indicator Tube (MGIT) and Lowenstein Jensen (LJ) from various clinical samples were included. We performed MGIT 1st and 2nd line susceptibility testing for tuberculosis. Results: Among the 61 isolates, 12 (19.6%) were multi drug resistant. Capreomycin resistance was observed in 17 (27.8%) isolates, kanamycin resistance in 30 (49.1%), ofloxacin resistance in 5 (8.1%), and ethionamide resistance in 6 (9.8%) isolates. Resistance to kanamycin and ethionamide was more common among patients with multi drug resistant tuberculosis (MDR-TB) than among those with non-MDR-TB. Conclusion: The MGIT system has surpassed solid culture and is an excellent method for performing culture and drug sensitivity testing for tuberculosis. However, its use remains limited by economic and logistical challenges. The high prevalence of aminoglycoside resistance suggests the need to preserve these drugs for treating patients with MDR-TB. https://ijm.tums.ac.ir/index.php/ijm/article/view/5160 https://ijm.tums.ac.ir/index.php/ijm/article/download/5160/1840