en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <span style="font-size:11pt"><span style="line-height:normal"><span sans-serif="" style="font-family:Calibri,"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Introduction</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">:<b> </b></span></span><span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">Tuberculosis, caused by<i> Mycobacterium tuberculosis</i>, is one of the most common infectious diseases worldwide.<i> </i>Epidemiological studies of <a name="_Hlk152158413"><i>M. tuberculosis</i> </a>drug resistance are critical for improving patient treatment approaches and controlling the spread of tuberculosis. The present study aimed to determine antibiotic resistance among <i>M. tuberculosis</i> clinical isolates using the</span></span></span></span> <span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">Microplate Alamar Blue Assay (MABA). </span></span></span></span><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Methods</span></span></b><span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">: In this descriptive cross-sectional study, 25 <i>M. tuberculosis</i> 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 16 software. </span></span></span></span><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Results</span></span></b><span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">:</span></span></span></span> <span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">Among the 25 investigated isolates, the frequencies for MDR, Pre-XDR, and XDR isolates were 20%, 8%, and 32%, respectively. The highest rate of drug resistance was to isoniazid (80%), rifampicin, and ethambutol (76%), and the highest rate of sensitivity was to moxifloxacin (68%). The frequency of isoniazid mono-resistance and rifampicin mono-resistance was 5 cases (50%) and 4 cases (40%), respectively.</span></span></span></span> <b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Conclusion:</span></span></b> <span style="font-size:10.0pt"><span style="background:white"><span new="" roman="" style="font-family:" times=""><span style="color:#222222">Our study revealed an alarming rate of MDR and XDR <i>M. tuberculosis</i> 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.</span></span></span></span></span></span></span> Mycobacterium tuberculosis, Bedaquiline, Microplate Alamar Blue Assay, Multi-drug resistance, Extensive drug-resistant tuberculosis 174 178 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-538-1&slc_lang=en&sid=1 Kamal Ahmadi kamalrokh1990@gmail.com 0000-0002-9830-6651 No 1Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; 2Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran; 3Student Research Committee, Pasteur Institute of Iran, Tehran, Iran Nahid Madadi-Goli nahidmadadi67@gmai.com 0000-0002-4531-3081 No 1Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; 2Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran; 3Student Research Committee, Pasteur Institute of Iran, Tehran, Iran Morteza Masoumi mortezamasoumi46@yahoo.com 0000-0002-6182-0980 No 1Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; 2Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran Mahshid Nasehi mnasehi@yahoo.com 0000-0002-2913-4294 No 4Department of Epidemiology and Biostatistics, School of Public Health, Iran University of Medical Sciences, Tehran, Iran; 5Center for Communicable Diseases Control, Ministry of Health and Medical Education, Tehran, Iran Seyed Davar Siadat sd_siadat@yahoo.com 0000-0002-6892-5603 No 1Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; 2Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran Farzam Vaziri farzam_vaziri@yahoo.com 0000-0001-7788-2548 No 1Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; 2Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran Abolfazl Fateh afateh2@gmail.com 0000-0002-2043-8523 Yes Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran; Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran