Genotypic Characterization of Drug-Susceptible and Drug-Resistant Mycobacterium tuberculosis Complex Isolates in Central Iran Using 24-Locus MIRU-VNTR Analysis

Abstract

Background: Identifying the genotypes of Mycobacterium tuberculosis (MTB) enables the classification of tuberculosis (TB) isolates at the strain level and facilitates phylogenetic analysis of the bacterium. This study aimed to determine and evaluate the genetic diversity and phylogenetic relationships of both drug-susceptible and drug-resistant Mycobacterium tuberculosis complex (MTBC) isolates with respect to first-and second-line anti-tuberculosis drugs using the 24-locus Mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) genotyping approach. Methods: A total of 81 MTBC isolates, including both drug-susceptible and drug-resistant strains, were collected from patients with pulmonary and extrapulmonary tuberculosis. All collected isolates were then subjected to genotyping using the 24-locus MIRU-VNTR method. Results: Among the 81 MTBC isolates, 72 distinct MIRU-VNTR patterns were identified. Of these, six were clustered together, while 66 isolates exhibited unique patterns. The identified genotypes included Delhi/CAS (35 isolates), NEW-1 (25 isolates), LAM (eight isolates), H37Rv (four isolates), Beijing (three isolates), Mycobacterium bovis (three isolates), URAL (two isolates), and UgandaI (one isolate). Conclusion: The Delhi/CAS genotype was the most common, while the UgandaI genotype was the least common among the studied isolates. Additionally, isoniazid-resistant isolates were more frequently observed within the Delhi/CAS genotype compared to others; however, no specific genotype was linked to drug resistance. © 2026 The Author(s).