[Composition of oropharyngeal microbiota in patients with COVID-19 of different pneumonia severity].

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.

[Prevalence and prognostic value of gastroenterological manifestations of COVID-19: data from the Russian University Clinic].

AIM: Assessment of the prevalence and prognostic value of gastroenterological manifestations in patients with COVID-19. MATERIALS AND METHODS: A single-center retrospective cohort study was carried out. Only cases with laboratory confirmed detection of SARS-CoV-2 virus RNA using polymerase chain reaction in oro-/nasopharyngeal smear samples were subject to analysis. Patients with documented (according to anamnestic data and/or according to examination data during hospitalization) organic pathology of the gastrointestinal tract (GIT) and/or hepatobiliary system, malignant neoplasms of any localization, as well as pregnant patients were excluded from the general register of retrospective data. The final cohort was divided into two groups depending on the presence of gastrointestinal symptoms: COVID-19 with gastrointestinal symptoms (cases) and COVID-19 without gastrointestinal symptoms (control). RESULTS: The final sample consisted of 3764 patients, including 2108 (56%) women and 1656 (44%) men. The average age of the subjects included in the analysis was 58.0 years (95% confidence interval CI 48.663.0). In the study cohort, gastroenterological manifestations (alone or in combination) were recorded in 885 (23.51%) patients. Calculation of the odds ratio (OR) of unfavorable and lethal outcomes between the analyzed groups showed that the presence of gastroenterological symptoms significantly increases the chances of lethal outcome in a cohort of elderly and senile patients (OR 1.6817, 95% CI 1.03352.7364; p=0.0364), determines a higher risk of hospitalization or transfer to the intensive care unit (OR 1.2959, 95% CI 1.05471.5922; p=0.0136), development of acute respiratory distress syndrome (OR 1.5952, 95% CI 1.31641.9329; p0.0001), as well as the need for mechanical ventilation (OR 1.2849, 95% CI 1.0771.5329; p=0.0054). CONCLUSION: The present study has demonstrated that gastroenterological symptoms are detected in about one in four patients infected with the SARS-CoV-2 virus and multiply the risk of adverse and life-threatening complications of COVID-19.