Molecular epidemiological monitoring of the tuberculosis pathogen in the Arkhangelsk region

Abstract

Introduction. Against the background of improvement of the main epidemiological indicators (morbidity and mortality) for tuberculosis in the Arkhangelsk region, the proportion of newly diagnosed tuberculosis patients with multidrug-resistant pathogen (MDR-TB) increased from 18.7% in 2002 to 33.8% in 2018.
 The purpose of this study was the genotypic characterization of Mycobacterium tuberculosis strains obtained from newly diagnosed tuberculosis patients in the Arkhangelsk region in 2018.
 Materials and methods. 89 M. tuberculosis strains isolated in 2018 from newly diagnosed tuberculosis patients were studied. Beijing genotype, its clusters B0/W148 and Central Asian/Russian were determined by PCR detection of the specific markers: IS6110 insertions in the dnaA-dnaN region, mutations in codons 48 of the mutT4 gene (CGG GGG) and 58 of the mutT2 gene (GGA CGA), IS6110 insertions in the Rv2664 region-Rv2665 and Rv1359-Rv1360, substitutions G A in the sigE gene. Non-Beijing strains were spoligotyped.
 Results. Drug resistance was detected in 41.6% (37/89), MDR — in 33.7% of strains. In 90% (27/30) of MDR strains, resistance to rifampicin and isoniazid was due to rpoB Ser531Leu and katG Ser315Thr mutations. Following M. tuberculosis genotypes were identified: Beijing (67.4%), T (14.6%), Ural (4.5%), Haarlem (4.5%), LAM (2.3%) and CAS1-Delhi (1.1%). Among the Beijing strains, clusters Central-Asian/Russian (60%; 36/60) and B0/W148 (30%; 18/60) prevailed. The majority of MDR strains belonged to the Beijing family (93.3%; 28/30), of which 64.3% (18/28) and 21.4% (6/28) belonged to clusters B0/W148 and Central-Asian/Russian, respectively.
 Conclusion. In heterogeneous population of the causative agent of tuberculosis in the Arkhangelsk region, the most common strains were those of the Beijing genotype; in 2018 its share increased to 67.4% (40.4% in 1998–1999). Among MDR strains, the proportion of Beijing reached 93.3%, of which more than half (64.3%) belonged to the epidemiologically and clinically significant in Russia cluster B0/W148.