Epidemiology of tuberculosis as a long-standing biological challenge and genetic characterization of Mycobacterium tuberculosis strains in the Republic of North Ossetia — Alania: A cross-sectional and cohort study

Introduction. Tuberculosis represents a long-standing biological challenge, and its impact on public health can be examined through epidemiological evaluation. Alongside traditional analysis of key disease indicators, molecular-genetic monitoring is a crucial component of epidemiological assessment. It enables identifying and tracking specific Mycobacterium tuberculosis strains circulating in a population. The aim of this study was to examine the epidemiology of tuberculosis as a long-standing biological challenge together with the genetic characterization of contemporary M. tuberculosis strains circulating in the Republic of North Ossetia–Alania. Methods. This mixed-design study (cohort and cross-sectional) consisted of two parts and employed epidemiological and microbiological (molecular-genetic) methods. A cohort analysis of all tuberculosis cases registered in the Republic of North Ossetia–Alania was conducted from 2014 to 2024. The epidemiological method evaluated the prevalence of pulmonary tuberculosis and served as the background for the bacteriological (molecular-genetic) cross-sectional study of the genotypes of M. tuberculosis strains circulating in the region, conducted from January to August 2024. Epidemiological indicators were obtained from federal statistical reporting forms and Rosstat. For genotyping, the total cohort of patients with active pulmonary tuberculosis under follow-up in the Republican Clinical Center for Phthisiopulmonology from January to August 2024 was considered (n = 230). Among them, 82 patients had newly diagnosed pulmonary tuberculosis; of these, 40 excreted the bacteria. Strain affiliation to the Beijing genotype and its subtypes B0/W148 and Central-Asian/Russian in culture-positive cases was determined using PCR detection of specific markers. All strains underwent spoligotyping, followed by comparative analysis with published datasets from neighboring territories and entries in the international SITVIT2 database. Results. Between 2014 and 2024, the Republic of North Ossetia–Alania demonstrated a marked decline in tuberculosis incidence and mortality — from 49.7 to 20.4 and from 9.1 to 1.5 per 100,000 population, respectively. From January to August 2024, 82 newly diagnosed cases of pulmonary tuberculosis were registered, and 40 M. tuberculosis cultures were isolated from bacteria-excreting patients. Of the genotyped strains, 41.7% (15/36) belonged to the Beijing genotype, with characteristic spoligotypes SIT 1 and SIT 265. The remaining strains belonged to the LAM (19.4%), T (22.2%), Haarlem (8.3%), and Ural (5.6%) families. Drug sensitivity was retained in 73.9% (17/23) of non-Beijing strains; 85.7% (7/8) of multidrug-resistant (MDR) isolates were of the Beijing genotype. Within the Beijing lineage, the dominant subtypes were Central-Asian/Russian (60.0%; 9/15) and B0/W148 (33.3%; 5/15), with all B0/W148 isolates demonstrating MDR. Rifampicin and isoniazid resistance was associated with rpoB Ser531Leu and katG Ser315Thr mutations. Conclusion. In the Republic of North Ossetia — Alania, the tuberculosis situation has stabilized with a trend toward improvement; however, the proportion of primary multidrug-resistant tuberculosis has significantly increased. Molecular-genetic analysis of M. tuberculosis isolates from newly diagnosed patients in 2024 revealed a heterogeneous pathogen population dominated by Beijing-genotype strains (42%). Although the proportion of the Russian epidemic Beijing subtype B0/W148 (13.9%) was relatively low, all such strains exhibited multidrug resistance. High population migration from neighboring Caucasus states with unstable socioeconomic conditions may contribute to the spread of MDR tuberculosis in North Ossetia — Alania and adjacent Russian regions, indicating the need for continued and geographically expanded study.

1. Zudin AB, Shhepin VO. Global`ny`e vy`zovy` dlya Rossijskogo zdravooxraneniya [Global challenges for the Russian healthcare]. Byulleten` Nacional`nogo nauchno-issledovatel`skogo instituta imeni N.A. Semashko. 2016;5:42–47 (In Russ.).

2. Bagcchi S. WHO’s Global Tuberculosis Report 2022. Lancet Microbe. 2023;4(1):e20. https://doi.org/10.1016/S2666-5247(22)00359-7

3. Narkevich AN, Koretskaya NM, Vinogradov KA, Narkevich AA. Influence of age, gender and social factors on risk of occurrence of pulmonary tuberculosis. Pulmonologiya. 2013;4:73–76 (In Russ.). https://doi.org/10.18093/0869-0189-2013-0-4-73-76

4. Onishchenko GG, Smolenskii VYu, Ezhlova EB, Demina YuV, Toporkov VP, Toporkov AV, Lyapin MN, Kutyrev VV. Conceptual bases of biological safety. Part 1. Annals of the Russian academy of medical sciences. 2013;68(10):4–13 (In Russ.). http://dx.doi.org/10.15690/vramn.v68i10.781

5. Hancharou A. Modern virology and biological threats of an infectious nature. Science and Innovations. 2023;2:16–23 (In Russ.).

6. Hao R, Liu Y, Shen W, Zhao R, Jiang B, Song H, Yan M, Ma H. Surveillance of emerging infectious diseases for biosecurity. Sci China Life Sci. 2022;65(8):1504–1516. https://doi.org/10.1007/s11427-021-2071-x

7. Berman A.M. Impact of biological challenges on social and political relations:issues and prospects. Vestnik VGUES. 2020;4:79–86 (In Russ.). https://doi.org/10.24866/VVSU/2073-3984/2020-4/079-087

8. Albert C, Baez A, Rutland J. Human security as biosecurity Reconceptualizing national security threats in the time of COVID-19. Politics Life Sci. 2021;40(1):83–105. https://doi.org/10.1017/pls.2021.1

9. Onishchenko GG, Popova AYu, Toporkov VP, Smolensky VYu, Shcherbakova SA, Kutyrev VV. Present-Day Menaces and Challenges in the Sphere of Biological Safety and Strategy of Countermeasures. Problems of Particularly Dangerous Infections. 2015;3:5–9 (In Russ.). https://doi.org/10.21055/0370-1069-2015-3-5-9

10. Chakaya J, Khan M, Ntoumi F, Aklillu E, Fatima R, Mwaba P, Kapata N, Mfinanga S, Hasnain SE, Katoto PDMC, Bulabula ANH, Sam-Agudu NA, Nachega JB, Tiberi S, McHugh TD, Abubakar I, Zumla A. Global Tuberculosis Report 2020 — Reflections on the Global TB burden, treatment and prevention efforts. Int J Infect Dis. 2021;113 (Suppl 1):S7–S12. https://doi.org/10.1016/j.ijid.2021.02.107

11. Wang X, Shang A, Chen H, Li J, Jiang Y, Wang L, Qiu S, Sun F, Yue C. Global, regional, and national disease burden of multidrug-resistant tuberculosis without extensive drug resistance, 1990–2021: Findings from the Global Burden of Disease Study 2021. Drug Resist Updat. 2025;82:101265. https://doi.org/10.1016/j.drup.2025.101265

12. Zagdyn ZM, Kobesov NV, Pagieva MK, Vasiliev MD, Galoyan AS. Gender-age peculiarities of disability-adjusted life years (DALYs) in tuberculosis in a high-density region: a retrospective cohort study. Kuban Scientific Medical Bulletin. 2024;31(2):27–40 (In Russ.). https://doi.org/10.25207/1608-6228-2024-31-2-27-40

13. Kobesov NV, Sinitsin MV, Zagdyn ZM, Pagieva MK. The Influence of the COVID-19 Pandemic on the Detection, Diagnosis and Treatment in the Republic of North Ossetia — Alania. Ural Medical Journal. 2024;23(3):16–25 (In Russ.). https://doi.org/10.52420/umj.23.3.16

14. Zhdanova SN, Ogarkov OB, Savilov ED, Kondratov IG. Application of New Molecular Genetic Strategies for Transborder Transmission Analysis of Tuberculosis in Irkutsk Region. Epidemiology and Vaccinal Prevention. 2022;21(2):59–65 (In Russ.). https://doi.org/10.31631/2073-3046-2022-21-2-59-65

15. Vyazovaya A, Gerasimova A, Mudarisova R, Terentieva D, Solovieva N, Zhuravlev V, Mokrousov I. Genetic Diversity and Primary Drug Resistance of Mycobacterium tuberculosis Beijing Genotype Strains in Northwestern Russia. Microorganisms. 2023;11(2):255. https://doi.org/10.3390/microorganisms11020255

16. Lebedeva IB, Zhdanova SN, Kondratov IG, Sybil KV, Ogarkov OB, Brusina EB. Genetic structure and drug resistance of Mycobacterium tuberculosis strains in the Kemerovo Region — Kuzbass. Journal of microbiology, epidemiology and immunobiology. 2023;100(6):428– 441 (In Russ.). https://doi.org/10.36233/0372-9311-449

17. Zagdyn ZM, Kobesov NV, Russkikh SV, Vasilyeva TP, Galoyan AS. The methodological approaches to evaluation of effect of tuberculosis as socially significant infection on decreasing of public health quality. Problemi socialnoi gigieni, zdravookhranenia i istorii meditsini. 2024;32(2):187–195 (In Russ.). http://dx.doi.org/10.32687/0869-866X-2024-32-2-187-195

18. van Embden JD, Cave MD, Crawford JT, Dale JW, Eisenach KD, Gicquel B, Hermans P, Martin C, McAdam R, Shinnick TM, et al. Strain identification of Mycobacterium tuberculosis by DNA fingerprinting: recommendations for a standardized methodology. J Clin Microbiol. 1993;31(2):406–409. https://doi.org/10.1128/jcm.31.2.406-409.1993

19. Kamerbeek J, Schouls L, Kolk A, van Agterveld M, van Soolingen D, Kuijper S, Bunschoten A, Molhuizen H, Shaw R, Goyal M, van Embden J. Simultaneous detection and strain differentiation of Mycobacterium tuberculosis for diagnosis and epidemiology. J Clin Microbiol. 1997;35(4):907–914. https://doi.org/10.1128/jcm.35.4.907-914.1997

20. Sek N, Kakadiy I. Ethnopolitical Ossetian-Ingush conflict. Bulletin of Science and Practice. 2019:5(7):298–303 (In Russ.). http://dx.doi.org/10.33619/2414-2948/44/40

21. Vasilyeva IА, Testov VV, Sterlikov SА. Tuberculosis situation in the years of the COVID-19 pandemic — 2020–2021. Tuberculosis and Lung Diseases. 2022:100(3);6–12 (In Russ.) http://doi.org/10.21292/2075-1230-2022-100-3-6-12

22. Schwartz Y, Vyazovaya A, Tursunova N, Mokrousov I. Impact of the COVID-19 pandemic on the epidemiology and clinical course of tuberculosis: expected and paradoxical consequences. BMC Infect Dis. 2025;25(1):417. http://doi.org/10.1186/s12879-025-10793-x

23. Andreevskaya SN, Larionova EE, Kiseleva EA, Chernousova LN, Ergeshov AЕ. Comparative Molecular Genetic Characteristics of Mycobacterium tuberculosis Cultures Isolated in the European Part of the Russian Federation in 1998–2003 and 2016–2021. Tuberculosis and Lung Diseases. 2023;101(3):27–36 (In Russ.). https://doi.org/10.58838/2075-1230-2023-101-3-27-36

24. Umpeleva TV, Mazurina EА, Vakhrusheva DV, Eremeeva NI. Comparison of different methods for drug susceptibility testing of Mycobacterium tuberculosis to rifampicin. Tuberculosis and Lung Diseases. 2022;100(1);41–48 (In Russ.). http://doi.org/10.21292/2075-1230-2022-100-1-41-48

25. Eliseev PI, Bayrakova AL, Gandzhalyan TA, Zorina VV, Balantsev GA, Maryandyshev АO. Monitoring of Mutations Associated with Drug Resistance of Mycobacterium tuberculosis. Tuberculosis and Lung Diseases. 2025;103(1):45–53 (In Russ.). https://doi.org/10.58838/2075-1230-2025-1031-45-53

26. Coll F, Phelan J, Hill-Cawthorne GA, Nair MB, Mallard K, Ali S, Abdallah AM, Alghamdi S, Alsomali M, Ahmed AO, Portelli S, Oppong Y, Alves A, Bessa TB, Campino S, Caws M, Chatterjee A, Crampin AC, Dheda K, Furnham N, Glynn JR, Grandjean L, Minh Ha D, Hasan R, Hasan Z, Hibberd ML, Joloba M, Jones-López EC, Matsumoto T, Miranda A, Moore DJ, Mocillo N, Panaiotov S, Parkhill J, Penha C, Perdigão J, Portugal I, Rchiad Z, Robledo J, Sheen P, Shesha NT, Sirgel FA, Sola C, Oliveira Sousa E, Streicher EM, Helden PV, Viveiros M, Warren RM, McNerney R, Pain A, Clark TG. Genome-wide analysis of multi- and extensively drug-resistant Mycobacterium tuberculosis. Nat Genet. 2018;50(2):307–316. https://doi.org/10.1038/s41588-017-0029-0

27. Walker TM, Miotto P, Köser CU, Fowler PW, Knaggs J, Iqbal Z, Hunt M, Chindelevitch L, Farhat M, Cirillo DM, Comas I, Posey J, Omar SV, Peto TE, Suresh A, Uplekar S, Laurent S, Colman RE, Nathanson CM, Zignol M, Walker AS; CRyPTIC Consortium; Seq&Treat Consortium; Crook DW, Ismail N, Rodwell TC. The 2021 WHO catalogue of Mycobacterium tuberculosis complex mutations associated with drug resistance: A genotypic analysis. Lancet Microbe. 2022;3(4):e265–e273. https://doi.org/10.1016/S2666-5247(21)00301-3

28. Shebzukhova TA, Vartumyan AA, Vasilyeva IA. The North Caucasus in Russia’s geopolitical strategy. Modern Science and Innovations. 2024;3:202-210 (In Russ.). https://doi.org/10.37493/2307-910X.2024.3.22

29. Niemann S, Diel R, Khechinashvili G, Gegia M, Mdivani N, Tang YW. Mycobacterium tuberculosis Beijing lineage favors the spread of multidrug-resistant tuberculosis in the Republic of Georgia. J Clin Microbiol. 2010;48(10):3544–3550. https://doi.org/10.1128/JCM.00715-10

30. Pardini M, Niemann S, Varaine F, Iona E, Meacci F, Orrù G, Yesilkaya H, Jarosz T, Andrew P, Barer M, Checchi F, Rinder H, Orefici G, Rüsch-Gerdes S, Fattorini L, Oggioni MR, Bonnet M. Characteristics of drug-resistant tuberculosis in Abkhazia (Georgia), a high-prevalence area in Eastern Europe. Tuberculosis (Edinb). 2009;89(4):317– 324. https://doi.org/10.1016/j.tube.2009.04.002

31. Pfyffer GE, Strässle A, van Gorkum T, Portaels F, Rigouts L, Mathieu C, Mirzoyev F, Traore H, van Embden JD. Multidrug-resistant tuberculosis in prison inmates, Azerbaijan. Emerg Infect Dis. 2001;7(5):855– 861. https://doi.org/10.3201/eid0705.017514