Current Clinical Importance of Fecal Microbiota Transplantation Treatment (FMT) in Liver Diseases and Liver Transplant (LT) Recipients

The gut microbiota (GM) constitutes a complex, metabolically active “organ” weighing 1–2 kg and comprising more than 100 tril-lion microorganisms whose collective genome far exceeds that of the human host. Culture-independent sequencing techniques have clarified its taxonomic structure and functional roles in host metabolism, immunity, and inflammation, and have established the bidirectional “gut–liver axis” as a key pathway in liver homeostasis and disease. Dysbiosis, increased intestinal permeability, and altered bile acid and microbial metabolite profiles contribute to the pathogenesis and progression of a broad spectrum of liver diseases, including viral hepatitis (HBV, HCV, HEV, HAV, HDV), alcoholic liver disease, metabolic dysfunction-associated steatotic liver disease, autoimmune hepatitis, primary sclerosing cholangitis, cirrhosis, drug-induced liver injury, and hepatocellular carcinoma. Characteristic disease-specific shifts in bacterial composition and diversity have been described and may serve as potential diagnostic or prognostic biomarkers. Fecal microbiota transplantation (FMT) has emerged as an effective strategy to restore intestinal microecological balance, with robust evidence for antibiotic-refractory Clostridioides difficile infection and encouraging early data in chronic hepatitis B, severe alcoholic hepatitis, and PSC. In liver transplantation (LT) recipients, who are highly susceptible to infections and profound post-transplant changes in GM, FMT appears to be a safe and potentially valuable adjunct, particularly for recurrent C. difficile infection. Overall, modulation of the gut microbiota through FMT, probiotics, prebiotics, bacteriophages, and targeted antibiotics represents a promising avenue for prevention and treatment of liver diseases and for improving outcomes after LT, although large, well-designed prospective studies are still needed to define indications, protocols, and long-term safety.

Keywords: Gut microbiota, gut–liver axis, fecal microbiota transplantation, liver transplantation