{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T00:58:22Z","timestamp":1772499502361,"version":"3.50.1"},"reference-count":47,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T00:00:00Z","timestamp":1771200000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pathogens"],"abstract":"<jats:p>Early and rapid diagnosis of drug resistance in tuberculosis (TB) plays a key role in reducing the spread of resistance and enabling effective treatment. The aim of this study was to investigate mutations in drug resistance-associated gene regions of Mycobacterium tuberculosis complex (MTBC) isolates resistant to at least two first-line anti-tuberculosis drugs through sequence analysis, in order to characterize the core molecular features of these strains in the region and to identify previously unreported, geographically distinct novel mutation sites. The drug susceptibility of 23 clinical isolates was assessed using the BACTEC MGIT 960 system, and resistance-associated point mutations were identified through DNA sequence analysis and comparison with GenBank reference sequences. AAG \u2192 AGG mutation was detected in the rpsL gene region at codon 43 (n = 7) and codon 88 (n = 1). Additionally, GAG \u2192 GCG point mutation was identified at codon 70 (n = 2), representing a new region not previously reported in the literature. The most frequent mutation was AGC \u2192 ACC at katG codon 315 (n = 10), followed by a C \u2192 T substitution at position \u221215 of the inhA promoter region (n = 4). Additionally, TCG \u2192 TTG at rpoB codon 531 (n = 4) and ATG \u2192 GTG at embB codon 306 (n = 1) were detected. The detection of resistance-associated mutations is essential for controlling drug-resistant tuberculosis. In this study, a novel rpsL mutation (GAG \u2192 GCG) at codon 70 and a previously unreported codon 88 mutation in our country were identified, contributing to the understanding of molecular resistance mechanisms and epidemiology.<\/jats:p>","DOI":"10.3390\/pathogens15020222","type":"journal-article","created":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T11:11:28Z","timestamp":1771240288000},"page":"222","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Investigation of Gene Regions Responsible for Drug Resistance in Clinical Isolates of Mycobacterium tuberculosis Complex Resistant to at Least Two First-Line Anti-Tuberculosis Drugs"],"prefix":"10.3390","volume":"15","author":[{"given":"Mahmut","family":"Ulger","sequence":"first","affiliation":[{"name":"Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Mersin, 33169 Mersin, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nurcihan","family":"Biltekin","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Mersin, 33169 Mersin, T\u00fcrkiye"},{"name":"Institute of Health Sciences, Department of Pharmaceutical Microbiology, University of Mersin, 33169 Mersin, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0823-3680","authenticated-orcid":false,"given":"Seda Tezcan","family":"Ulger","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology, Faculty of Medicine, University of Mersin, 33343 Mersin, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gonul","family":"Aslan","sequence":"additional","affiliation":[{"name":"Department of Medical Microbiology, Faculty of Medicine, University of Mersin, 33343 Mersin, T\u00fcrkiye"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,16]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2024). Global Tuberculosis Report 2024, World Health Organization. Available online: https:\/\/www.who.int\/teams\/global-tuberculosis-programme\/tb-reports."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"112175","DOI":"10.1016\/j.ejmech.2020.112175","article-title":"Repurposed drug candidates for antituberculosis therapy","volume":"192","author":"An","year":"2020","journal-title":"Eur. J. Med. Chem."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"101574","DOI":"10.1016\/j.cimid.2020.101574","article-title":"Drug resistant Tuberculosis: A review","volume":"74","author":"Khawbung","year":"2021","journal-title":"Comp. Immunol. Microbiol. Infect. Dis."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1138","DOI":"10.1093\/jac\/dkx506","article-title":"Evolution of drug resistance in Mycobacterium tuberculosis: A review on the molecular determinants of resistance and implications for personalized care","volume":"73","author":"Dookie","year":"2018","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Rocha, D.M.G.C., Viveiros, M., Saraiva, M., and Os\u00f3rio, N.S. (2021). The Neglected Contribution of Streptomycin to the Tuberculosis Drug Resistance Problem. Genes, 12.","DOI":"10.3390\/genes12122003"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"20","DOI":"10.4046\/trd.2019.0065","article-title":"Treatment of Isoniazid-Resistant Pulmonary Tuberculosis","volume":"83","author":"Jhun","year":"2020","journal-title":"Tuberc. Respir. Dis."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"102083","DOI":"10.1016\/j.tube.2021.102083","article-title":"Mechanisms and detection methods of Mycobacterium tuberculosis rifampicin resistance: The phenomenon of drug resistance is complex","volume":"128","author":"Xu","year":"2021","journal-title":"Tuberculosis"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"112","DOI":"10.4103\/ijpvm.IJPVM_114_19","article-title":"Frequency of Codon 306 Mutations in embB Gene of Mycobacterium tuberculosis Resistant to Ethambutol: A Systematic Review and Meta-Analysis","volume":"11","author":"Mohammadi","year":"2020","journal-title":"Int. J. Prev. Med."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Liebenberg, D., Gordhan, B.G., and Kana, B.D. (2022). Drug resistant tuberculosis: Implications for transmission, diagnosis, and disease management. Front. Cell. Infect. Microbiol., 12.","DOI":"10.3389\/fcimb.2022.943545"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"520","DOI":"10.1016\/j.eimc.2017.01.015","article-title":"Rapid diagnosis of tuberculosis. Detection of drug resistance mechanisms","volume":"35","author":"Vitoria","year":"2017","journal-title":"Enferm. Infecc. Microbiol. Clin."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1016\/j.jgar.2017.07.004","article-title":"Genetic diversity of Mycobacterium tuberculosis and transmission associated with first-line drug resistance: A first analysis in Jalisco, Mexico","volume":"11","year":"2017","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"ref_12","unstructured":"Sa\u011fl\u0131k Bakanl\u0131\u011f\u0131, T.C. (2025, November 02). Ulusal Mikrobiyoloji Standartlar\u0131: Ulusal T\u00fcberk\u00fcloz Tan\u0131 Rehberi (UTTR), Available online: https:\/\/hsgm.saglik.gov.tr\/depo\/birimler\/mikrobiyoloji-referans-laboratuvarlari-ve-biyolojik-urunler-db\/Dokumanlar\/Rehberler\/0_TuberkulozRehberi_UTTR.pdf."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2425","DOI":"10.1128\/JCM.42.6.2425-2431.2004","article-title":"Molecular characterization of rifampin- and isoniazid-resistant Mycobacterium tuberculosis strains isolated in Poland","volume":"42","author":"Sajduda","year":"2004","journal-title":"J. Clin. Microbiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"830","DOI":"10.1016\/j.resmic.2004.06.007","article-title":"Characterisation of rpsL, rrs and embB mutations associated with streptomycin and ethambutol resistance in Mycobacterium tuberculosis","volume":"155","author":"Tracevska","year":"2004","journal-title":"Res. Microbiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"255","DOI":"10.7883\/yoken.JJID.2008.255","article-title":"Genotypic analysis of isoniazid and rifampin resistance in drug-resistant clinical Mycobacterium tuberculosis complex isolates in southern Turkey","volume":"61","author":"Aslan","year":"2008","journal-title":"Jpn. J. Infect. Dis."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"951706","DOI":"10.1155\/2015\/951706","article-title":"Mutations Found in embCAB, embR, and ubiA Genes of Ethambutol-Sensitive and Resistant Mycobacterium tuberculosis Clinical Isolates from China","volume":"2015","author":"Xu","year":"2015","journal-title":"Biomed Res. Int."},{"key":"ref_17","unstructured":"World Health Organization (2023). Catalogue of Mutations in Mycobacterium Tuberculosis Complex and Their Association with Drug Resistance, World Health Organization. [2nd ed.]. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240082410."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Alsayed, S.S.R., and Gunosewoyo, H. (2023). Tuberculosis: Pathogenesis, Current Treatment Regimens and New Drug Targets. Int. J. Mol. Sci., 24.","DOI":"10.3390\/ijms24065202"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.jgar.2017.01.005","article-title":"Frequency of rrs and rpsL mutations in streptomycin-resistant Mycobacterium tuberculosis isolates from Iranian patients","volume":"9","author":"Khosravi","year":"2017","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"ref_20","first-page":"115","article-title":"Streptomisine diren\u00e7li Mycobacterium tuberculosis kompleks izolatlarinda rpsL ve rrs gen b\u00f6lgesi mutasyonlarinin ara\u015ft\u0131r\u0131lmas\u0131 [Investigation of rpsL and rrs gene region mutations in streptomycin resistant Mycobacterium tuberculosis complex isolates]","volume":"43","author":"Ulger","year":"2009","journal-title":"Mikrobiyol. Bul."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"309","DOI":"10.7883\/yoken.JJID.2005.309","article-title":"Molecular analysis of isoniazid, rifampin and streptomycin resistance in Mycobacterium tuberculosis isolates from patients with tuberculosis in D\u00fczce, Turkey","volume":"58","author":"Ozturk","year":"2005","journal-title":"Jpn. J. Infect. Dis."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"87","DOI":"10.15625\/2615-9023\/18156","article-title":"Characterization of mutations conferring streptomycin resistance in Mycobacterium tuberculosis in Vietnam","volume":"45","author":"Huy","year":"2023","journal-title":"Acad. J. Biol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Feuerriegel, S., Oberhauser, B., George, A.G., Dafae, F., Richter, E., R\u00fcsch-Gerdes, S., and Niemann, S. (2012). Sequence analysis for detection of first-line drug resistance in Mycobacterium tuberculosis strains from a high-incidence setting. BMC Microbiol., 12.","DOI":"10.1186\/1471-2180-12-90"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s00284-022-03043-9","article-title":"Evaluation of Mutations Related to Streptomycin Resistance in Mycobacterium tuberculosis Clinical Isolates","volume":"79","author":"Shafipour","year":"2022","journal-title":"Curr. Microbiol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"e146643","DOI":"10.5812\/jcma-146643","article-title":"Characterization of rrs and rpsL Mutations in Aminoglycoside-Resistant Mycobacterium tuberculosis Strains Isolated from Clinical Specimens in the West of Iran","volume":"9","author":"Farzamfar","year":"2024","journal-title":"J. Cell. Mol. Anesth."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1111\/j.1469-0691.2009.02800.x","article-title":"Analysis of rpsL and rrs mutations in Beijing and non-Beijing streptomycin-resistant Mycobacterium tuberculosis isolates from Singapore","volume":"16","author":"Sun","year":"2010","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/j.jgar.2015.11.009","article-title":"Mutations in rrs, rpsL and gidB in streptomycin-resistant Mycobacterium tuberculosis isolates from Thailand","volume":"4","author":"Smittipat","year":"2016","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"ref_28","first-page":"30","article-title":"rrs and rpsL mutations in streptomycin-resistant isolates of Mycobacterium tuberculosis from Mexico","volume":"46","year":"2013","journal-title":"Tuberculosis"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3379","DOI":"10.2147\/IDR.S320024","article-title":"Prevalence and Molecular Characteristics Based on Whole Genome Sequencing of Mycobacterium tuberculosis Resistant to Four Anti-Tuberculosis Drugs from Southern Xinjiang, China","volume":"14","author":"Anwaierjiang","year":"2021","journal-title":"Infect. Drug Resist."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"84","DOI":"10.54453\/TMCD.2023.89421","article-title":"T\u00fcberk\u00fclozlu Hastalara Ait Mycobacterium tuberculosis Kompleks \u0130zolatlar\u0131n\u0131n MIRU-VNTR ve Spoligotiplendirme Y\u00f6ntemleri ile Genotiplendirilmesi","volume":"53","author":"Biltekin","year":"2023","journal-title":"Turk. Mikrobiyol. Cemiy. Derg."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"235","DOI":"10.5578\/tt.6474","article-title":"Analysis of rpsL and rrs genes mutations related to streptomycin resistance in Mdr and Xdr clinical isolates of Mycobacterium tuberculosis","volume":"63","author":"Arjomandzadegan","year":"2015","journal-title":"Tuberk. Toraks"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"45","DOI":"10.5578\/mb.20239904","article-title":"Etambutole Diren\u00e7li ve Duyarl\u0131 Mycobacterium tuberculosis Kompleksi Klinik \u0130zolatlar\u0131nda embA, embB ve embC Gen B\u00f6lgesi Mutasyonlar\u0131","volume":"57","author":"Aslan","year":"2023","journal-title":"Mikrobiyol. Bul."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"e01279-17","DOI":"10.1128\/AAC.01279-17","article-title":"Mutations within embCAB Are Associated with Variable Level of Ethambutol Resistance in Mycobacterium tuberculosis Isolates from China","volume":"62","author":"Sun","year":"2017","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"3125","DOI":"10.2147\/IDR.S466371","article-title":"Different Contributions of embB and ubiA Mutations to Variable Level of Ethambutol Resistance in Mycobacterium tuberculosis Isolates","volume":"17","author":"Nan","year":"2024","journal-title":"Infect. Drug Resist."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"317","DOI":"10.3390\/antibiotics3030317","article-title":"Drug resistance mechanisms in Mycobacterium tuberculosis","volume":"3","author":"Palomino","year":"2014","journal-title":"Antibiotics"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"305","DOI":"10.5578\/mb.57614","article-title":"\u0130zoniazide Diren\u00e7li Mycobacterium tuberculosis \u0130zolatlar\u0131nda Minimal \u0130nhibit\u00f6r Konsantrasyonun ve Gen Mutasyonlar\u0131n\u0131n Belirlenmesi","volume":"51","author":"Uzun","year":"2017","journal-title":"Mikrobiyol. Bul."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"227","DOI":"10.4103\/lungindia.lungindia_204_19","article-title":"Pattern of InhA and KatG mutations in isoniazid monoresistant Mycobacterium tuberculosis isolates","volume":"37","author":"Charan","year":"2020","journal-title":"Lung India"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Isakova, J., Sovkhozova, N., Vinnikov, D., Goncharova, Z., Talaibekova, E., Aldasheva, N., and Aldashev, A. (2018). Mutations of rpoB, katG, inhA and ahp genes in rifampicin and isoniazid-resistant Mycobacterium tuberculosis in Kyrgyz Republic. BMC Microbiol., 18.","DOI":"10.1186\/s12866-018-1168-x"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1639","DOI":"10.1111\/j.1469-0691.2010.03267.x","article-title":"Detection of rpoB, katG and inhA gene mutations in Mycobacterium tuberculosis clinical isolates from Chongqing as determined by microarray","volume":"16","author":"Yao","year":"2010","journal-title":"Clin. Microbiol. Infect."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Kigozi, E., Kasule, G.W., Musisi, K., Lukoye, D., Kyobe, S., Katabazi, F.A., Wampande, E.M., Joloba, M.L., and Kateete, D.P. (2018). Prevalence and patterns of rifampicin and isoniazid resistance conferring mutations in Mycobacterium tuberculosis isolates from Uganda. PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0198091"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"333","DOI":"10.2147\/IDR.S144446","article-title":"Diversity and evolution of drug resistance mechanisms in Mycobacterium tuberculosis","volume":"10","year":"2017","journal-title":"Infect. Drug Resist."},{"key":"ref_42","first-page":"461","article-title":"PrimerAntit\u00fcberk\u00fcloz \u0130la\u00e7lara Diren\u00e7li MycobacterumTuberculosis Kompleks \u0130zolatlar\u0131nda Diren\u00e7le \u0130li\u015fkili Yayg\u0131n Mutasyonlar\u0131n Ara\u015ft\u0131r\u0131lmas\u0131","volume":"51","author":"Akpolat","year":"2024","journal-title":"Dicle T\u0131p Derg."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1089\/mdr.2005.11.94","article-title":"Molecular characterization of isoniazid and rifampin resistance of Mycobacterium tuberculosis clinical isolates from Malatya, Turkey","volume":"11","author":"Aktas","year":"2005","journal-title":"Microb. Drug Resist."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.jgar.2020.02.026","article-title":"Mutations in rpoB and katG genes and the inhA operon in multidrug-resistant Mycobacterium tuberculosis isolates from Zambia","volume":"22","author":"Solo","year":"2020","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Yenew, B., Kebede, A., Alemu, A., Diriba, G., Mehammed, Z., Amare, M., Dagne, B., Sinshaw, W., Tesfaye, E., and Beyene, D. (2024). Genotypic and phenotypic drug resistance patterns of Mycobacterium tuberculosis isolated from presumptive pulmonary tuberculosis patients in Ethiopia: A multicenter study. PLoS ONE, 19.","DOI":"10.1371\/journal.pone.0303460"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1967675","DOI":"10.1155\/2022\/1967675","article-title":"Frequency of rpoB, katG, and inhA Gene Polymorphisms Associated with Multidrug-Resistant Mycobacterium tuberculosis Complex Isolates among Ethiopian TB Patients: A Systematic Review","volume":"2022","author":"Seid","year":"2022","journal-title":"Interdiscip. Perspect. Infect. Dis."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Nguyen, T.N.A., Anton-Le Berre, V., Ba\u00f1uls, A.L., and Nguyen, T.V.A. (2019). Molecular Diagnosis of Drug-Resistant Tuberculosis; A Literature Review. Front. Microbiol., 10.","DOI":"10.3389\/fmicb.2019.00794"}],"container-title":["Pathogens"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/2\/222\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T11:43:21Z","timestamp":1771242201000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-0817\/15\/2\/222"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,16]]},"references-count":47,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["pathogens15020222"],"URL":"https:\/\/doi.org\/10.3390\/pathogens15020222","relation":{},"ISSN":["2076-0817"],"issn-type":[{"value":"2076-0817","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,16]]}}}