No abstract

The microbiota of the respiratory tract remains a relatively poorly studied subject. At the same time, like the intestinal microbiota, it is involved in modulating the immune response to infectious agents in the host organism. A causal relationship between the composition of the respiratory microbiota and the likelihood of development and the severity of COVID-19 may be hypothesized. We analyze biomaterial from nasopharyngeal smears from 336 patients with a confirmed diagnosis of COVID-19, selected during the first and second waves of the epidemic in Russia. Sequences from a similar study conducted in Spain were also included in the analysis. We investigated associations between disease severity and microbiota at the level of microbial community (community types) and individual microbes (differentially represented species). To search for associations, we performed multivariate analysis, taking into account comorbidities, type of community and lineage of the virus. We found that two out of six community types are associated with a more severe course of the disease, and one of the community types is characterized by high stability (very similar microbiota profiles in different patients) and low level of lung damage. Differential abundance analysis with respect to comorbidities and community type suggested association of Rothia and Streptococcus genera representatives with more severe lung damage, and Leptotrichia, unclassified Lachnospiraceae and Prevotella with milder forms of the disease.

Ancient sublineage of the Mycobacterium tuberculosis Beijing genotype is endemic and prevalent in East Asia and rare in other world regions. While these strains are mainly drug susceptible, we recently identified a novel clonal group Beijing 1071-32 within this sublineage emerging in Siberia, Russia and present in other Russian regions. This cluster included only multi/extensive drug resistant (MDR/XDR) isolates. Based on the phylogenetic analysis of the available WGS data, we identified three synonymous SNPs in the genes Rv0144, Rv0373c, and Rv0334 that were specific for the Beijing 1071-32-cluster and developed a real-time PCR assay for their detection. Analysis of the 2375 genetically diverse M. tuberculosis isolates collected between 1996 and 2020 in different locations (European and Asian parts of Russia, former Soviet Union countries, Albania, Greece, China, Vietnam, Japan and Brazil), confirmed 100% specificity and sensitivity of this real-time PCR assay. Moreover, the epidemiological importance of this strain and the newly developed screening assay is further stressed by the fact that all identified Beijing 1071-32 isolates were found to exhibit MDR genotypic profiles with concomitant resistance to additional first-line drugs due to a characteristic signature of six mutations in rpoB450, rpoC485, katG315, katG335, rpsL43 and embB497. In conclusion, this study provides a set of three concordant SNPs for the detection and screening of Beijing 1071-32 isolates along with a validated real-time PCR assay easily deployable across multiple settings for the epidemiological tracking of this significant MDR cluster.

Aim. To estimate the dynamics changes in the population structure of the tuberculosis (ТВ) pathogen in the Irkutsk region by comparison of genotypes of M. tuberculosis from patients of different age groups. Materials and methods. 588 epidemiologically unrelated strains of M. tuberculosis isolates from 567 ТВ patients were characterized using 24-locus MIRU-VNTR typing. 160 strains belonged to patients of different age groups. 59 strains were isolated from the «young» people with ТВ who were bom after 1990 and 101 isolates from people who were born before 1955. Results. Two-thirds of the samples (427/567) were genotype Beijing with the dominance of two subtypes belonging to the modem epidemic clonal complexes CC1 and CC2. The high level of clustering profiles of CC1 and CC2 genotype Beijing in «older» and «young» patients in the Irkutsk region indicates the presence and active transmission of epidemic CC1 and CC2 subtypes over the past fifty years.