Kamal Ahmadi - ۱Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; ۲Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran; ۳Student Research Committee, Pasteur Institute of Iran, Tehran, Iran
Nahid Madadi-Goli - ۱Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; ۲Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran; ۳Student Research Committee, Pasteur Institute of Iran, Tehran, Iran
Morteza Masoumi - ۱Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; ۲Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Mahshid Nasehi - ۴Department of Epidemiology and Biostatistics, School of Public Health, Iran University of Medical Sciences, Tehran, Iran; ۵Center for Communicable Diseases Control, Ministry of Health and Medical Education, Tehran, Iran
Seyed Davar Siadat - ۱Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; ۲Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Farzam Vaziri - ۱Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; ۲Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Abolfazl Fateh - Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran

Introduction: Tuberculosis, caused by Mycobacterium tuberculosis, is one of the most common infectious diseases worldwide. Epidemiological studies of M. tuberculosis drug resistance are critical for improving patient treatment approaches and controlling the spread of tuberculosis. The present study aimed to determine antibiotic resistance among M. tuberculosis clinical isolates using the Microplate Alamar Blue Assay (MABA). Methods: In this descriptive cross-sectional study, ۲۵ M. tuberculosis isolates from clinical samples were identified and confirmed using standard microbiological and biochemical tests. Then, the MIC for the antibiotics Bedaquiline, isoniazid, rifampin, ethambutol, ofloxacin, moxifloxacin, capreomycin, and streptomycin was determined using the MABA method. The results were analyzed using SPSS version ۱۶ software. Results: Among the ۲۵ investigated isolates, the frequencies for MDR, Pre-XDR, and XDR isolates were ۲۰%, ۸%, and ۳۲%, respectively. The highest rate of drug resistance was to isoniazid (۸۰%), rifampicin, and ethambutol (۷۶%), and the highest rate of sensitivity was to moxifloxacin (۶۸%). The frequency of isoniazid mono-resistance and rifampicin mono-resistance was ۵ cases (۵۰%) and ۴ cases (۴۰%), respectively. Conclusion: Our study revealed an alarming rate of MDR and XDR M. tuberculosis strains, indicating that current first-line treatments may be ineffective for a significant number of patients. The bedaquiline resistance among the isolates with no history of previous exposure to this drug suggests unexplored resistance mechanisms. Molecular techniques to accurately identify these mechanisms may contribute to developing more effective treatment strategies to combat drug-resistant tuberculosis.

Mycobacterium tuberculosis, Bedaquiline, Microplate Alamar Blue Assay, Multi-drug resistance, Extensive drug-resistant tuberculosis