Fecal microbiota transplant on Escherichia-Shigella gut composition and its potential role in the treatment of generalized anxiety disorder: A systematic review

The gut-brain-axis has a role in mental health disorders. In people with generalized anxiety disorder, GAD,1 normal flora Escherichia-Shigella, are significantly elevated. Fecal microbiota transplant, FMT,2 has been used to alter the gut composition in unhealthy individuals. There may be a role for FMT in the treatment of GAD to improve the gut-brain-axis. A systematic review of literature was conducted on articles published in PubMed, CINAHL Plus, Scopus, Cochrane Library, and Wed of Science from 2000 to 2022 that analyzed FMT as a modality to alter the gut microbiome in which Escherichia-Shigella levels were quantified and reported. Of 1916 studies identified, 14 fit criteria and were included. Recipients undergoing FMT procedures had at least one enteric diagnosis and increased percentages of Escherichia-Shigella pre-FMT. Five studies on recurrent Clostridioides difficile infection, three irritable bowel syndrome, two ulcerative colitis, one ulcerative colitis and recurrent Clostridioides difficile infection, one acute intestinal and chronic graft-vs-host disease, one pouchitis, and one slow transit constipation. 10 articles (71.4 %) showed decreased levels of Escherichia-Shigella post-FMT compared to pre-FMT. Four studies claimed the results were significant (40 %). Limitations include potential bias in study selection, study methods of analysis, and generalization of results. The gut-brain-axis has a role in GAD. Those with GAD have significantly higher Escherichia-Shigella compared to those without GAD. FMT has the potential to decrease Escherichia-Shigella in patients with GAD to positively alter the gut-brain-axis as a potential for future GAD treatment.