**Conflict of interest**

*Human Microbiome*

immune system [38].

cases [38–40].

immune system. This feature is the reason why ongoing research carries so much interest in correcting dysbiosis using fecal microbiota transplantation [37, 38].

In patients with ulcerative colitis and Crohn's disease, preliminary clinical studies showed a long-term follow-up clinical remission maintained, even endoscopic and histologic remission in a few other cases. A meta-analysis of nine studies showed a remission rate of 36.2%. Still, the results depend on some factors like age (higher remission in younger patients with ages between 7 and 20 years old), route of administration (naso-jejunal tube, enema, colonoscopy), and dose and preparation of donor feces. Also, it seems like fecal microbiota transplant is more effective in Crohn's disease than in ulcerative colitis with remission rates of 60.5 and 22%, respectively. On the other hand, a study involving 15 patients with steroid-dependent ulcerative colitis who received fecal microbiota transplant through colonoscopy showed a long-term maintained remission in 57% of

Because of the lack of uniformity regarding the treatment protocols and the delivery method, it is hard to offer a solid conclusion referring to the safety and efficacy of fecal microbiota transplant in inflammatory bowel disease. If compared with the results collected in cases of recurrent *Clostridium difficile* infection (remission in about 90%), these results may look discouraging. Still, we have to keep in mind that the inflammatory bowel disease's pathogenesis is not purely driven by dysbiosis as it happens in *Clostridium difficile* infection. Following this direction, we need more randomized controlled placebo studies to clarify the role of fecal micro-

These can be classified into short-term and long-term side effects [19]. Short-term side effects are related to the delivery method. They may include mild fever, flatulence, constipation, diarrhea, vomiting, and abdominal discomfort, but all of these usually resolve in a few weeks. In cases when FMT was administered through the naso-jejunal tube, patients presented with high fever and the rise of the C-reactive protein. When using colonoscopy, there have been reported cases of

Due to the lack of research, there are few data collected about the dominant concern regarding the safety of fecal microbiota transplant—long-term side effects. We can speculate a considerable risk for chronic diseases, involving obesity, diabetes, colon cancer, and atherosclerosis, due to the alteration of intestinal microbiota

Inflammatory bowel diseases are chronic, relapsing intestinal disorders, with pathogenesis not fully elucidated. Treatment disappointments are still high, despite the availability of different therapeutic options. Patients' reduced compliance, the impoverished life of quality, and the increased economic, sanitary, and social burden worldwide are still unresolved issues. For that reason, research must continue to identify more information about the intestinal microbiota, metabolic pathways, and

biota transplant in inflammatory bowel disease [40–42].

perforation, bleeding, and symptoms related to anesthesia [43].

**4.3 Potential adverse effects of FMT**

FMT can reduce IBD's severity by increasing the production of short-chain fatty acids (butyrate); this way, the bowel permeability is reduced, and the integrity of the gut epithelium is maintained. Also, inhibiting the production of inflammatory elements, leukocyte adhesion, and the activity of T cells, FMT may restore the

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[43, 44].

**5. Conclusions**

All authors declare "no conflict of interest."
