Julia S. Galeeva

Background: Periodontitis is a chronic inflammatory disease mostly associated with Porphyromonas gingivalis infection and characterized by progressive destruction of the supporting structures of the tooth, including the gingiva, periodontal ligament and alveolar bone. However, the impact of other members of the periodontal microbiome on stage of the severity of the periodontitis remains largely uncharacterized. Methods: This exploratory study employs whole-genome shotgun (WGS) metagenomics to characterize the periodontal microbiome in patients suffering from mild and severe periodontitis, aiming to identify microbial signatures linked to disease severity via analysis of taxonomic composition, predicted metabolic pathways and metagenome-assembled genomes (MAGs). After initial selection, 28 adult patients with a computer tomography (CT)-confirmed diagnosis of mild and severe stage of periodontitis from 2 clinics were included in the research project. Results: Taxonomic analysis confirms the presence of various commensal and pathogenic bacteria detectable at the species level, especially belonging to so-called “red, orange and green periodontal complexes”—P. gingivalis, T. forsythia, C. rectus, and Capnocytophaga spp. that may contribute to disease heterogeneity. The conducted investigation suggests that non-microbial factors such as cardiovascular diseases and antibiotic usage in the last 6 months prior to the hospital admission could explain variance of disease progression and impact on severity. Analysis of microbial functional composition revealed metabolic traits showing positive correlations with severe stage of periodontitis. Robust network analysis suggested interactions between pathogenic bacteria of the red complex and other members of the periodontal microbiome. Conclusions: These findings underscore the multifactorial nature of periodontitis pathogenesis, highlighting the need for integrated approaches combining microbial, host, and environmental data to unravel drivers of disease progression. The study provides a foundation for future large-scale investigations into personalized diagnostic or therapeutic strategies.

The exponential growth of viral metagenomic data has created an urgent need for accurate and scalable tools for virus discovery, yet the extreme diversity, rapid evolution, and limited reference databases for viruses pose unique computational challenges that traditional sequence comparison methods struggle to address. This systematic review, conducted in accordance with PRISMA 2020, examines current trends and methodological advances in virus discovery tools from 1990 to 2025. As virus discovery is a broad and multi-dimensional topic, this review focuses on the first-line tools used to analyze the results of high-throughput sequencing. The review was conducted using the PubMed database with a snowballing approach, with over 54 key studies selected for the analysis. These studies encompass the following approaches: alignment-based methods, rapid similarity estimation techniques, profile hidden Markov model methods, combination pipelines, k-mer-based approaches, and machine learning-based methods. The transition from alignment-based to machine learning methods has dramatically improved the detection of divergent viruses, yet challenges remain in interpreting model decisions and handling incomplete viral genomes. This review summarizes current knowledge and potential future directions for the development of virus detection capabilities.

Relevance. The COVID-19 pandemic caused by the SARS-CoV-2 virus has demonstrated the critical importance of understanding the mechanisms of transmission and finding effective methods of prevention. Particular attention has been paid to the role of oral hygiene, as the oral cavity serves as a major route of transmission. Studies show that the composition of the oral microbiota can influence the course and outcome of COVID-19 disease. Therefore, there is a need to study the effects of oral antiseptics on the microbiome, which may offer new opportunities for the prevention and treatment of this disease.Objective. The aim of this study is to evaluate the effectiveness of the oral cleansing foam «Parodontol PROF» in reducing the pathogenic microflora of the oral cavity in patients with COVID-19 and to assess its effect on the risk of secondary infections.Materials and methods. The study was conducted on the basis of the Clinical Medical Centre «Kuskovo» of Russian University of Medicine. It included 450 patients with a confirmed diagnosis of COVID-19. The participants were divided into two groups: the test group used oral cleansing foam, while the control group used no additional oral hygiene. Comparative analyses of the taxonomic composition of the oropharyngeal microbiota and dental plaque before and after the use of the cleansing foam were performed.Results. The study showed that patients who regularly used the cleansing foam «Parodontol PROF» had a significant decrease in the representation of pathogens, including Mycoplasma, and an increase in the number of beneficial commensals such as Lactococcus and Lactobacillus. These changes indicate the potential efficacy of this product to improve oral hygiene and reduce the risk of secondary infections.Conclusion. The study supports the hypothesis that improving oral hygiene with specialised antiseptic agents, such as a cleansing foam, may help to reduce pathogenic microflora in the oral cavity in patients with COVID-19. This, in turn, may reduce the risk of pathogen migration into the lower respiratory tract and the development of secondary infections. The findings emphasise the importance of further research in this area and the development of comprehensive approaches to oral hygiene management in the context of infectious diseases.

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has significantly impacted global healthcare, underscoring the importance of exploring the virus’s effects on infected individuals beyond treatments and vaccines. Notably, recent findings suggest that SARS-CoV-2 can infect the gut, thereby altering the gut microbiota. This study aimed to analyze the gut microbiota composition differences between COVID-19 patients experiencing mild and severe symptoms. We conducted 16S rRNA metagenomic sequencing on fecal samples from 49 mild and 43 severe COVID-19 cases upon hospital admission. Our analysis identified a differential abundance of specific bacterial species associated with the severity of the disease. Severely affected patients showed an association with Enterococcus faecium, Akkermansia muciniphila, and others, while milder cases were linked to Faecalibacterium prausnitzii, Alistipes putredinis, Blautia faecis, and additional species. Furthermore, a network analysis using SPIEC-EASI indicated keystone taxa and highlighted structural differences in bacterial connectivity, with a notable disruption in the severe group. Our study highlights the diverse impacts of SARS-CoV-2 on the gut microbiome among both mild and severe COVID-19 patients, showcasing a spectrum of microbial responses to the virus. Importantly, these findings align, to some extent, with observations from other studies on COVID-19 gut microbiomes, despite variations in methodologies. The findings from this study, based on retrospective data, establish a foundation for future prospective research to confirm the role of the gut microbiome as a predictive biomarker for the severity of COVID-19.

Background The global healthcare landscape has changed dramatically as a result of the COVID-19 pandemic caused by SARS-CoV-2. In addition to focusing on treatments and vaccines, it is crucial to investigate the effects of the virus on infected individuals. Recent studies have discovered that SARS-CoV-2 can infect the gut, affecting the gut microbiota and revealing a new aspect of the virus. This study examined the differences in gut microbiota composition between COVID-19 patients with severe and mild conditions. Methods In this study, we utilized 16S rRNA metagenomic sequencing to examine the fecal samples obtained from 49 patients with mild and 43 patients with severe cases of COVID-19 upon their admission to the hospital. Results Differential abundance analysis with respect to comorbidities on the 313 most abundant ASVs suggested an association of Enterococcus faecium, Rothia mucilaginosa, Akkermansia muciniphila, Schaalia odontolytica, Eubacterium limosum, and Slackia isoflavoniconvertens species with a severe condition, and Faecalibacterium prausnitzii, Ruminococcoides bili, Turicibacter sanguinis, Alistipes putredinis, Bacteroides vulgatus, Bacteroides stercoris, Lachnospiraceae bacterium sunii NSJ-8, Blautia faecis, and Anaerostipes hadrus with a milder course of the disease. Network analysis using SPIEC-EASI revealed keystone taxa and structural differences between the mild and severe groups, suggesting an increased level of bacterial connectivity disruption within the severe group. Conclusion Our study highlights the diverse impacts of SARS-CoV-2 on the gut microbiome among both mild and severe COVID-19 patients, showcasing a spectrum of microbial responses to the virus. Importantly, these findings align, to some extent, with observations from other studies on COVID-19 gut microbiomes, despite variations in methodologies.

The microbiota of the respiratory tract remains a relatively poorly studied subject. At the same time, it is involved in modulating the immune response to infectious agents in the host organism, just like the intestinal microbiota. A relationship between the composition of the respiratory microbiota and the likelihood of development and the severity of COVID-19 may be assumed. In this study, we applied the 16S rRNA metagenomic sequencing to analyze the oropharyngeal swabs from 120 COVID-19 patients collected during the first and the second waves of the COVID-19 epidemic in Russia. Differential abundance analysis with respect to comorbidities suggested association of Neisseria oralis, Neisseria mucosa, unidentified Veillonella spp., Lautropia mirabilis species with more severe lung damage, and Streptococcus salivarius, Capnocytophaga sputigena and Haemophilus parahaemolyticus with a milder course of the disease. We hypothesize that the latter bacteria (or some of them) might be beneficial for the respiratory tract and might be able to alleviate the course of the COVID-19 disease.

Background. Exocrine pancreatic insufficiency (EPI) is a critical host factor in determining the composition of the gut microbiota. Diseases that cause exocrine insufficiency can affect the gut microbiome, which can potentiate disease progression and complications. To date, the relationship of exocrine insufficiency in various pancreatic (PA) pathologies, in chronic pancreatitis (CP), with dysbiotic changes in the intestinal microbiota (IM) has not been reliably studied. The available data are heterogeneous and contradictory, which determines the need for further research. Aim. To conduct a comparative analysis of the taxonomic composition of the intestinal microbiota in patients with CP of various etiologies, without or with the presence of EPI of varying severity, as well as patients with severe EPI with a history of surgical intervention (SI) on the pancreas. Materials and methods. A total of 85 patients were included in the study. Patients were divided into groups according to the severity of EPI: Group 1 (n=16) patients with CP without EPI; Group 2 (n=11) patients with CP and mild EPI; Group 3 (n=17) patients with severe CP and EPI; Group 4 (n=41) severe EPI in persons with a history of SI on the pancreas. Verification of CP was carried out according to clinical, anamnestic and instrumental data. The degree of EPI was determined by the level of pancreatic elastase-1 (PE-1) feces. Informed consent for the study was obtained for each patient, an anamnesis was collected, physical and laboratory examinations were performed, and a stool sample was obtained. DNA was extracted from each stool sample, the taxonomic composition of BM was determined by sequencing the bacterial 16S rRNA genes, followed by bioinformatic analysis. Results. We followed the changes in the gut microbiota from a group of patients with CP without EPI to a group with severe EPI, in those who underwent SI. At the level of the phylum, the IM of all groups showed the dominance of Firmicutes, with the lowest representation in the severe EPI group, both with SI and CP, and the growth of the Actinobacteria, Verrucomicrobiota and Fusobacteria types. The differential representation of childbirth varied: in patients with severe EPI and CP, compared with mild, statistically significant genera Akkermansia, Ruminococcus gauvreauii group and Holdemanella; compared with CP without exocrine insufficiency, Prevotella, Ruminococcus gauvreauii group, Peptostreptococcus and Blautia dominated. The CP group with mild EPI was dominated by the following genera: Lachnospiraceae_ND 2004 group, Faecalitalea, Fusobacterium, Catenibacterium, Roseburia, Atopobium, Cloacibacillus, Clostridium innococum group, Ruminococcus torques group. All groups showed a low diversity of taxa with a predominance of opportunistic flora, including participants in oncogenesis. Conclusion. The results of the study show that patients with CP of various etiologies and patients with severe EPI who underwent specific intervention on the pancreas have intestinal microbiota dysbiosis, the severity of which is significantly influenced by the degree of EPI.

The human respiratory tract is a complex system characterized by a series of niches colonized with specific microbial communities. Until recently, researchers were mostly interested in lung microbiomes associated with acute and chronic infections. The upper respiratory tract microbiota has gained attention during COVID-19 (COronaVIrus Disease 2019) pandemic because it was suspected to influence the course and the outcome of viral infections. Aim. In this two-part review (see part 1, Pul’monolog;iya. 2022; 32 (5): 745-754), we summarize current knowledge of the microbial communities at each upper respiratory tract location, considering the proposed barrier function of the respiratory microbiome. Conclusion. Based on the evidence presented in this review, we can see how the respiratory microbiome is involved in the pathogenesis of viral respiratory infections, including SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2).

Aim. To identify features of the taxonomic composition of the oropharyngeal microbiota of COVID-19 patients with different disease severity. Materials and methods. The study group included 156 patients hospitalized with confirmed diagnosis of COVID-19 in the clinical medical center of Yevdokimov Moscow State University of Medicine and Dentistry between April and June 2021. There were 77 patients with mild pneumonia according to CT (CT1) and 79 patients with moderate to severe pneumonia (CT2 and CT3). Oropharyngeal swabs were taken when the patient was admitted to the hospital. Total DNA was isolated from the samples, then V3V4 regions of the 16s rRNA gene were amplified, followed by sequencing using Illumina HiSeq 2500 platform. DADA2 algorithm was used to obtain amplicon sequence variants (ASV). Results. When comparing the microbial composition of the oropharynx of the patients with different forms of pneumonia, we have identified ASVs associated with the development of both mild and severe pneumonia outside hospital treatment. Based on the results obtained, ASVs associated with a lower degree of lung damage belong predominantly to the class of Gram-negative Firmicutes (Negativicutes), to various classes of Proteobacteria, as well as to the order Fusobacteria. In turn, ASVs associated with a greater degree of lung damage belong predominantly to Gram-positive classes of Firmicutes Bacilli and Clostridia. While being hospitalized, patients with severe pneumonia demonstrated negative disease dynamics during treatment significantly more often. Conclusion. We have observed differences in the taxonomic composition of the oropharyngeal microbiota in patients with different forms of pneumonia developed outside hospital treatment against COVID-19. Such differences might be due to the presumed barrier function of the oropharyngeal microbiota, which reduces the risk of virus titer increase.

Human respiratory tract is a complex system with a specific microbiological profile. Until recently, researchers were mostly interested in lung microbial communities associated with acute and chronic infections. The upper respiratory tract microbiota has gained attention during COVID-19 pandemic as it was proposed to be one of the factors affecting the course and the outcome of viral infections. The aim. In this review, we summarized the current knowledge about microbial communities in each section of the upper respiratory tract, considering the proposed barrier function of the respiratory microbiome. Conclusion. The facts provided in the first part of this review give a modern perspective on the structure of microbial communities of each part of the upper respiratory tract and factors that affect their variability.