The gut microbiota in patients with COVID‐19 and obesity

Massip Copiz, María Macarena

The COVID‐19 pandemic is caused by the novel coronavirus SARS‐CoV‐2. Obesity is one of the major comorbidities that are related to complications in the course of the disease. Obesity is characterized by a chronic low grade of inflammation and it is proposed that abnormal gut microbiota together with increased gut permeability are risk factors of this pathology. The aim of the present study was to conduct a descriptive research and investigate about the imbalance in the gastrointestinal microbiota (dysbiosis) in patients with COVID‐19 and obesity. A library research using the electronic databases PubMed and Google Scholar was performed. The full search strategy combined terms from three themes: COVID‐19, obesity, and gut microbiota. Terms were searched as both keywords (title/abstract words) and a comprehensive list of MeSH terms related to each theme. Titles and abstracts were reviewed for relevance and then screened considering the full text content. Network maps were also generated to evaluate the co‐ocurrence terms in the papers analyzed using VOSviewer 1.6.14 software. Several studies indicate that gut microbiota is altered in COVID‐19 patients showing a decrease in abundance and diversity. Different opportunistic pathogens were found increased in COVID‐19 patients including Collinsella, Streptococcus, Morganella, Rothia, Veillonella, Erysipelatoclostridium, Actinomyces, Coprobacillus and Clostridium. Many of them were associated with an increased in SARS‐CoV‐2 infectivity, inflammatory markers, or COVID‐19 disease severity. Fecal fungal microbiome was also altered showing an enrichment of fungal pathogens from the genera Candida and Aspergillus. There is a correlation between the bacterial species present in the gut microbiota of COVID‐19 patients and in patients with obesity. This was observed principally in the increment of Firmicutes, Actinobacteria and Proteobacteria and the decrease of Bacteroidetes. Modulation of gut microbiota with prebiotics, probiotics and synbiotics are suggested to be used in patients with COVID‐19. The present study contributes to highlight the importance of gastrointestinal microflora in COVID‐19 patients with obesity as well as the necessity to study specifically this population which report a higher risk of COVID‐19 morbidity and mortality. Further studies are needed to evaluate potential treatments to reestablish gut microbiome, reduce inflammation, and improve immune function considering the persistence of SARS‐CoV‐2 in the gastrointestinal tract.