Prevalence of the A2058G mutation in 23S rRNA gene, which determines Treponema pallidum macrolide resistance in Russian population

Objective. To investigate prevalence of the A2058G mutation in the Russian population of T. pallidum and its association with molecular subtypes. Materials and Methods. We analyzed DNA isolated from 325 samples of clinical material obtained from patients of dermatovenereological treatment and prophylactic institutions in 6 federal districts of the Russia in the period from 2014 to 2021. Patients were diagnosed with primary syphilis of the genital organs, primary syphilis of other sites, or secondary syphilis of the skin and mucous membranes. DNA was isolated using the Proba-NK reagent kit (DNA-technology, Russia) according to the manufacturer’s instructions. The presence of T. pallidum genetic material was confirmed by PCR with primers for the species-specific polA gene. Molecular typing was performed based on the analysis of polymorphic regions of species-specific T. pallidum genes. The primary decoding of the nucleotide sequences of the 23S rRNA gene fragment was carried out using the Sequencing Analysis 5.3.1 program. The analyzed fragments were aligned using the Mega 5 program. Results. Eight molecular subtypes of T. pallidum – 14d/f, 14d/g, 14b/f, 14c/f, 14i/f, 9d/f, 14b/g and 14e/f with stable dominance of subtype 14d/f – were identified in the Russian Federation in the interval 2014–2021. Three subtypes, 14d/g, 14b/g and 14b/f, carrying the A2058G mutation associated with azithromycin resistance, were identified. Conclusions. Studies on molecular typing of T. pallidum strains in the Russia have shown significant population heterogeneity. Three sublines containing the A2058G mutation were shown to exist, one of which – 14b/f – is described as rare. The obtained data confirm the relevance of continuous monitoring of the emergence of resistant strains and the development of new mutations.