In this blog Dr. John Ong, one the BMJOG trainee editors discusses the gastrointestinal manifestations of COVID-19. Whilst gastrointestinal COVID-19 infection is now well recognised its pathophysiology remains poorly understood. In this month’s blog, Dr. Ong briefly discuss two articles that may shed some light on the disease processes within the GI tract. In addition, from a clinical perspective a systematic review of the gastrointestinal and hepatic manifestations of COVID-19 was recently published in BMJOG and summarises prevalence, mortality by country, and intensive care admission rate across the globe.

The first study, titled “Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19” by Yeoh YK et al (Gut 2021;70:698–706), is a small observational study (n = 100 patients) from Hong Kong. The authors hypothesized that alteration of gut microbiota affected host immune responses in COVID-19 infection. Paired blood and stool samples were collected from patients with active COVID-19 infection confirmed by qPCR of nasopharyngeal swabs. Relationships between gut microbiota, serological markers of inflammation, and disease severity were then studied. Interestingly, the authors reported that gut microbiota with known immuno-modulatory associations such as Faecalibacterium prausnitzii, Eubacterium rectale and bifidobacteria, were significantly reduced in COVID-19 patients compared to non-COVID-19 patients. Furthermore, the depletion of these microbiotas were closely related to COVID-19 disease severity and persisted even until discharge. However, this study was limited by small sample size, restricted population, and the lack of a robust treatment control arm (e.g. COVID negative patients taking identical antibiotics for the same duration).

The second study, titled “Gastrointestinal mucosal damage in patients with COVID-19 undergoing endoscopy: an international multicentre study” by Vanella G et al (BMJ Open Gastro 2021;8:e000578), is an observational study that sought to characterise endoscopic lesions seen in COVID-19 patients. This was an international collaboration from 16 sites across 7 different countries during the first wave of the pandemic (data collected from February – May 2020). Interestingly, the authors reported that ischaemic-like colopathy was present in one-third of COVID-19 patients who had a lower GI endoscopy. They hypothesize that these findings could have been caused by anti-viral systemic inflammatory response and endothelitis that was been reported in COVID-19. However, it is noteworthy that the data was collected during a period where nearly all gastroenterology societies restricted endoscopies to patients with gastrointestinal bleeding only to curb the nosocomial spread of the virus. As such, small sample sizes and selection bias may have played a role in estimating the prevalence of ischaemic-like colopathy.

Nonetheless, further studies are needed to clarify the validity of these observations. If indeed true, faecal transplantation to restore gut microbiota and prophylactic anticoagulation may become treatment options for moderate to severe COVID-19 in the future!