Editor – I read with interest the article by Cooney and colleagues in which 43.8% of the patients studied reported new-onset gastrointestinal (GI) symptoms in the 6 months after their acute COVID-19 illness and the authors suggest the possible existence of a post-COVID-19 irritable bowel syndrome (IBS).1 The authors discuss the presence of the angiotensin converting enzyme 2 (ACE-2) receptor throughout the GI tract, which serves as the SARS-CoV-2 receptor, as an important potential factor. However, the potential relevance of gut microbiome disturbance in patients with COVID-19 was not discussed.
Significant alterations in the gut microbiome have been demonstrated in patients with COVID-19 compared with non-COVID-19 controls, characterised by an abundance of opportunistic pathogens and a reduction in certain gut commensals known to have anti-inflammatory properties including Faecalibacterium prausnitzii and Bifidobacterium.2 A meta-analysis also found significant reductions in both of these gut commensals in IBS patients when compared with healthy controls.2 Additionally, multiple studies have reported reduced levels of F prausnitzii in the gut of patients with inflammatory bowel disease.4
The degree of gut dysbiosis in COVID-19 has been demonstrated to correlate with the severity of COVID-19 illness and dysbiosis has been shown to persist in a subset of patients even after clearance of SARS-CoV-2 RNA.5,6 However, antibiotics are also likely to play a role, at least in part, supported by the fact that alterations in the gut microbiome have also been identified in patients treated for (non-COVID-19) community-acquired pneumonia.6 Empirical broad-spectrum antibiotic usage in patients hospitalised with COVID-19 is high (>60%), particularly in individuals with severe disease and, in the study by Cooney et al, 97% were admitted for inpatient care with 36% requiring intensive care unit care.1,7 Broad-spectrum antibiotics have been shown to negatively impact the gut microbiota resulting in reduced microbial diversity and potentially beneficial bacteria.8 Furthermore, an association between the use of certain antibiotic classes (macrolides and tetracyclines) within the prior 12 months and the development of IBS has been demonstrated.9 Gut microbiome dysbiosis may therefore play a key role in the development of post-COVID-19 GI symptoms and this area needs further study.
References
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