Tumenbayar, Oyuntuya

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Molecular epidemiological analysis of Mycobacterium tuberculosis isolates from rural population of nationwide tuberculosis prevalence survey in Mongolia
(Mongolian National University of Medical Sciences, 2025-12-26)
Oyuntuya Tumenbayar
;
Tsolmon Boldoo
;
Yoshiro Murase
;
Tsetsegtuya Borolzoi
;
Naranzul Dambaa
Objective: Mongolia is among the 30 high-burden countries for TB and DR-TB. Whole-genome sequencing (WGS) offers precise insights into TB transmission, strain diversity, and antimicrobial resistance (AMR), which are vital for TB control strategies. This study aimed to investigate the molecular epidemiology, lineage distribution, transmission clustering, and drug resistance patterns of M.tuberculosis collected from rural areas of Mongolia using NGS.Methods: A total of 50,194 individuals were screened in a national TB prevalence survey conducted according to WHO guidelines. From rural participants, 102 TB isolates were obtained; 100 with sufficient DNA quality were subjected to WGS. Bioinformatics analyses included lineage identification, AMR mutation profiling, and phylogenetic and clustering analyses. Results: Among the 100 isolates, lineage 2 (Beijing genotype) accounted for 72.0% and lineage 4 (Euro-American) for 28.0%. The Beijing type was dominant across all regions, especially the central region (84.6%) and showed high clustering (56.4%). A total of 13 clusters (≤12 SNVs) were identified; 86.6% were Beijing strains. MDR-TB comprised 10% of isolates, with 100% of MDR-TB strains belonging to the Beijing genotype. Resistance to isoniazid (23%) was common. Mutations associated with resistance were mainly found in katG, inhA, rpoB, pncA, rpsL, rrs, and embB genes. No resistance was observed to new drugs such as bedaquiline, linezolid, or clofazimine. Conclusions: In rural of Mongolia, M. tuberculosis Lineage 2 (modern Beijing genotype) is predominant, accounting for 72% of cases, with consistent distribution across geographic locations. Beijing strains demonstrated higher drug resistance compared to Euro-American types. Importantly, no resistance was detected to newly introduced TB drugs.
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Genetic Mutations Associated with Isoniazid Resistance in Mycobacterium tuberculosis in Mongolia
(2020-06)
Narmandakh, Erdenegerel
;
Tumenbayar, Oyuntuya
;
Borolzoi, Tsetsegtuya
;
Erkhembayar, Baasansuren
;
Boldoo, Tsolmon
Globally, mutations in the katG gene account for the majority of isoniazid-resistant strains of Mycobacterium tuberculosis Buyankhishig et al. analyzed a limited number of Mycobacterium tuberculosis strains in Mongolia and found that isoniazid resistance was mainly attributable to inhA mutations (B. Buyankhishig, T. Oyuntuya, B. Tserelmaa, J. Sarantuya, et al., Int J Mycobacteriol 1:40-44, 2012, https://doi.org/10.1016/j.ijmyco.2012.01.007). The GenoType MTBDRplus assay was performed for isolates collected in the First National Tuberculosis Prevalence Survey and the Third Anti-Tuberculosis Drug Resistance Survey to investigate genetic mutations associated with isoniazid resistance in Mycobacterium tuberculosis in Mongolia. Of the 409 isoniazid-resistant isolates detected by the GenoType MTBDRplus assay, 127 (31.1%) were resistant to rifampin, 294 (71.9%) had inhA mutations without katG mutations, 113 (27.6%) had katG mutations without inhA mutations, and 2 (0.5%) had mutations in both the inhA and katG genes. Of the 115 strains with any katG mutation, 114 (99.1%) had mutations in codon 315 (S315T). Of the 296 strains with any inhA mutation, 290 (98.0%) had a C15T mutation. The proportions of isoniazid-resistant strains with katG mutations were 25.3% among new cases and 36.2% among retreatment cases (P = 0.03) and 17.0% among rifampin-susceptible strains and 52.8% among rifampin-resistant strains (P < 0.01). Rifampin resistance was significantly associated with the katG mutation (adjusted odds ratio, 5.36; 95% confidence interval [CI], 3.3 to 8.67, P < 0.001). Mutations in inhA predominated in isoniazid-resistant tuberculosis in Mongolia. However, the proportion of katG mutations in isolates from previously treated cases was higher than in those from new cases, and the proportion in cases with rifampin resistance was higher than in cases without rifampin resistance.
Scopus© Citations 11

Tumenbayar, Oyuntuya

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