Gut Microbiota Dysbiosis Is a Crucial Player for the Poor Outcomes for COVID-19 in Elderly, Diabetic and Hypertensive Patients


Senior Member
The possibility that SARS-CoV-2 infection of enterocytes modify gut microbiota is supported by the fact that some patients with COVID-19 present intestinal dysbiosis (16, 17). There is evidence that hospitalized COVID-19 patients exhibit a significant reduction in gut microbiome diversity with depletion of beneficial bacterial symbionts and enrichment of opportunistic pathogens, including Actinomyces, Rothia, and Streptococcus (17, 18). Patients infected with SARS-CoV-2 also showed a decrease in the relative abundance of Faecalibacterium prausnitzii and Bifidobacterium bifidum, which are bacteria responsible for the production of butyrate (17, 19). Butyrate is a short-chain fatty acid (SCFA) that influences both the proliferation and differentiation of epithelial intestinal cells, by enhancing the renewal and integrity of the epithelial barrier function (20). Moreover, patients undergoing allogeneic hematopoietic cell transplantation showing greater abundance of butyrate-producing bacteria have five-fold protection against the development of viral lower respiratory tract infection (21).

Interestingly, there are several pathologies in which the gut microbiota is modified and in some of them a direct relationship has been found with the severity of COVID-19, including elderly, diabetes, hypertension, obesity, periodontitis, and kidney diseases, as summarized in Table 1. Among these conditions, aging, diabetes, and hypertension stand out, since they are the main cause of COVID-19-related death (9599). Yet, before getting into this point, it seemed worthwhile to discuss basic aspects of the gut microbiota, as well as the dysbiosis seen in aging and disease, particularly diabetes and hypertension.