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.
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.
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.
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).
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