Abstract

BackgroundSARS-CoV-2 is an RNA virus causing COVID-19. The clinical characteristics and epidemiology of COVID-19 have been extensively investigated, however studies focused on the patients microbiota are still lacking. In this study, we investigated the nasopharyngeal microbiome composition of patients who developed different severity levels of COVID-19. We performed Rdna-SSU (16S) sequencing from nasopharyngeal swab samples obtained from SARS-CoV-2 positive (56) and negative (18) patients in the province of Alicante (Spain) in their first visit to the hospital. Positive SARS-CoV-2 patients were observed and later categorized in mild (symptomatic without hospitalization), moderate (hospitalization) and severe (admission to ICU). We compared the microbiome diversity and OTU composition among severity groups using Similarity Percentage (SIMPER) analysis and Maaslin2. We also built bacterial co-abundance networks for each group using Fastpar. ResultsStatistical analysis indicated differences in the nasopharyngeal microbiome of COVID19 patients. 62 OTUs were found exclusively in SARS-CoV-2 positive patients, mostly classified as members of the phylum Bacteroidetes (18) and Firmicutes (25). OTUs classified as Prevotella were found to be significantly more abundant in patients that developed more severe COVID-19. Furthemore, co-abundance analysis indicated a loss of network complexity among samples from patients that later developed more severe symptoms. ConclusionsOur preliminary study shows that the nasopharyngeal microbiome of COVID-19 patients showed differences in the composition of specific OTUs and complexity of co-abundance networks. These microbes with differential abundances among groups could serve as biomarkers for COVID-19 severity. Nevertheless, further studies with larger sample sizes should be conducted to validate these results. IMPORTANCEThis work has studied the microbiota of the nasopharyngeal tract in COVID19 patients using advanced techniques of molecular microbiology. Diverse microorganisms, most of which are harmless or even beneficial to the host, colonize the nasopharyngeal tract. These microorganisms are the microbiota, and they are present in every people. However, changes in this microbiota could be related to different diseases as cancer, gastrointestinal pathologies or even COVID19. This study has been performed to investigate the microbiota from patients with COVID19, in order to determinate its implication in the pathology severity. The results obtained showed that it is possible that several specific microorganisms are present only in patients with severe COVID19. These data, could be used as a prognostic biomarker to early detect whose patients will develop a severe COVID19 and improve their clinical management.