Tuberculosis in Estonia: a major impact of Russian MDR Mycobacterium tuberculosis Beijing B0/W148-cluster

TB and MDR-TB incidence rates in Estonia are decreasing but remain higher than in most of EU. Here, we analyzed <i>Mycobacterium tuberculosis</i> population in Estonia and the results were viewed in the regional context. A total of 116 isolates from newly-diagnosed patients in 2014-2015 were genotyped. The Beijing genotype isolates were typed by 24 MIRU-VNTR loci, markers of modern/ancient sublineages and major epidemic clusters. The non-Beijing isolates were spoligotyped. The data were compared to MIRU-VNTRplus and SITVIT2 databases. The Beijing genotype was predominant (43/116; 37%) and included isolates of the modern sublineage. Most of them belonged to Beijing B0/W148 (n=24) and Beijing 94-32 (n=11) clusters. MDR was identified only in these two clusters and was strongly associated with B0/W148 (20/24) compared to 94-32-cluster (4/11). MIRU typing subdivided Beijing isolates into 18 types (HGI=0.76); type 100-32 included half of the Beijing isolates (21/43). The 73 non-Beijing isolates were subdivided into 33 spoligotypes and the main families: LAM (17/116; 15%), T (14%), Haarlem (13%), Ural (11%), X (2.6%). M. africanum (SIT326) was identified in 1 isolate. The non-Beijing isolates were mainly monoresistant. The prevalence of the Beijing genotype in Estonia (37%) is similar to the neighboring Russian Pskov region, 44% (Mokrousov et al., 2012) but is higher than in Latvia, 25% (Pole et al., 2019). Russian epidemic cluster Beijing B0/W148 is more prevalent in Estonia than in Latvia (49% vs 11%). To conclude, the current situation with TB in Estonia is seriously impacted by circulation of the MDR Beijing B0/W148-cluster. Supported by Russian Science Foundation (grant 19-14-00013).