Digestive system and severe acute respiratory syndrome coronavirus 2: New era of microbiome study and gastrointestinal tract manifestations during the coronavirus disease-19 pandemic

The main topic of this review article is the study of gastrointestinal disorders that were accompanying the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although SARS-CoV-2 primarily causes lung infection through binding to angiotensin-converting enzyme 2 (ACE2) receptors, intestinal epithelial cells, especially enterocytes of the small intestine, also express ACE2 receptors. Viral RNA and viral particles can be observed in feces for more than 30 days. It is also known that a respiratory viral infection causes disturbances in the gut microbiota. Diets, environmental factors, and genetics play an important role in the formation of the gut microbiota, which can affect the immune system. The diversity of the gut microbiota diminishes with age, which means that the fact that coronavirus disease (COVID-19) has proved to be mostly fatal in older patients further indicates the role that gut microbiota may play in this disease. It is, therefore, plausible that the gut microbiota could be a new therapeutic target and that probiotics could also have a role in the management of the patients affected by COVID-19.