OR01

1:Department of Infectious Diseases, Children's Infectious Diseases and Phthisiology, Kharkiv National Medical University, Kharkiv, Ukraine; 2:Molecular and Experimental Mycobacteriology Group, Research Center Borstel, Borstel, Germany; 3:Outpatient Department, Merefa Central District Hospital, Merefa, Ukraine; 4:National Scientific Center of Phthisiatry, Pulmonology and Allergology named after F. G. Yanovskyi, National Academy of Medical Sciences of Ukraine, Kiev, Ukraine; 5:Office of Cyber Infrastructure and Computational Biology, U.S. National Institute of Allergy and Infectious Diseases, Rockville, MD, USA; 6:Central Scientific and Research Laboratory, Kharkiv National Medical University, Kharkiv, Ukraine

Objective.To study tuberculosis (TB) epidemiology in Ukraine incl. the distribution of strains of different Mycobacterium tuberculosis complex (Mtbc) lineages and drug resistance rates among pulmonary tuberculosis patients across Ukraine between 2020 and 2023 based on high resolution whole genome sequencing (WGS) analysis.Methods.We conducted a nationwide study enrolling culture-confirmed TB patients across 18 regions of Ukraine (2020–2023).WGS was performed on 4,332 Mtbc isolates using Illumina sequencing platforms.Lineages (L) and genotypic resistance profiles were determined via the bioinformatic pipeline MTBseq.Clinical, microbiological, and epidemiological data were curated in the NIAID TB Portals. Results.Out of the 4,332 Mtbc stains,3,245 (74.9%) were at least resistant to rifampicin (RR), 2,005 (46.3%) Mtbc strains were classified as multidrug resistant (MDR). Resistance to fluoroquinolone was detected in 1,183 (27.3%) Mtbc strains, 1,086 strains (33.5% of RR) were classified as pre-extensively drug resistant (XDR). Strains of L2 (Beijing) accounted for 69.9% of the strains investigated, followed by strains of L4 (30.0%). The prevalence of L2 strains significantly increased from 66.9% in 2020 to 71.7% in 2023 (p≤0.05). L2 strains were dominant in 13 out of 18 regions (p≤0.001), while L4 strains were more prevalent in a minority of western regions of Ukraine. Furthermore, L2 strains were more frequently MDR, and pre-XDR than L4 strains. Conclusions.Our findings demonstrate high rates of fluoroquinolone resistance, especially in L2 strains, which potentially compromise the use of the new shorter drug-resistant TB regiments.These results underscore the dynamic molecular landscape of TB in Ukraine and highlight the need for lineage-adapted surveillance and treatment strategies.