Table 2.

Summary of studies about faecal microbiota transplantation (FMT) in chronic liver diseases (CLD).

Study	Aetiology	Sample Size	Patients Characteristics	FMT Type	Donors	Main Objective	Secondary Aim
Allegretti JR. 2019 [81]	PSC	10	No cirrhosis, 9 UC and 1 CD, only with mesalamine or azathioprine, and 4-week washout period for UDCA	By colonoscopy 90 mL bowel preparation with polyethylene glycol on the day before.	A single healthy donor	Safety: no adverse events related to FMT.	30% experienced a decrease in ALP ≥ 50% during the 24 weeks. Early changes in diversity as from first week that were maintained to 24 weeks. Increase in short-chain fatty acid producing genera. Correlation between the abundance of engrafter OTUs and a decrease in ALP Levels. No changes in stool bile acid profile clustering.
Bajaj J. 2021 [82]	AUD	20	Cirrhosis with a MELD score of 8.9 points	Placebo or FMT enema 1:1 (90 mL, 27 g stool, 2.7 × 1012 CFU)	OpenBiome where donor selection was performed to maximize Lachnospiraceae and Ruminococcaceae, which were lacking in the patients	Safety: 2 patients in FMT group had an adverse event but FMT-unrelated	Reduction of craving in 90%, psychosocial QOL improved and reduction in urinary EtG/creatinine. Reduction in systemic inflammation (IL-6) and in intestinal permeability (lower LBP). Microbial diversity increased with higher Ruminococcaceae and other SCFA producing taxa.
Bajaj J. 2017 [61]	Several	20	Cirrhotic with recurrent HE (at least two overt HE episodes requiring therapy), MELD < 17 and no active alcohol abuse.	5 days of antibiotics prior to FMT enema (Three frozen-then-thawed FMT units; 90 mL); Lactulose and rifaximin were continued.	1 donor with the optimal microbiota deficient in HE (Lachnospiraceae and Ruminococcacea)	Safety: at 150 days, 2 patients (20%) in FMT group had an adverse event but FMT-unrelated.	No FMT patients developed further HE in 5 months follow up vs. 50% in SOC. Improvement in PHES total score and EncephalApp Stroop. Increase in diversity and beneficial taxa (Lactobacillaceae, Bifidobacteriaceae, Lachnospiraceaeae and Ruminococcaceae). MELD score transiently worsened post-antibiotics.
Bajaj J. 2019 [85]	Several	20	Cirrhotic outpatients with recurrent HE	5 days of pre-FMT antibiotics 90 mL enema containing 2.7 × 1012 CFU	A single donor: rich in Lachnospiraceae and Ruminococcaceae	Well-tolerated.	Reduced need for hospitalization and HE episodes. Increase in diversity and increase in relative abundance of Burkholderiaceae and decreased Acidaminoccocaceae but not in Lachnospiraceae and Ruminococcaceae.
Bajaj J. 2019 [77]	Several	20	Cirrhotic patients with recurrent HE with MELD < 17.	15 FMT capsules (4.125 g stool) at once vs. placebo No pre-antibiotic therapy	A single donor rich in Lachnospiraceae and Ruminococcaceae	Safe and well-tolerated.	One patient had an HE (related to TIPS) vs. 3 patients in SOC (1 of them 5 episodes). No differences in stool diversity at day 30. Post-FMT, duodenal mucosal diversity increased with higher Ruminococcaceae, Bifidobacteriaceae and lower Streptococcaceae and Veillonellaceae. Reduction in Veillonellaceae was seen post-FMT in sigmoid and stool. IL-6 and serum LBP reduced post-FMT.
Bajaj J. 2021 [80]	Several	40 (20 + 20)	Cirrhotic outpatients with recurrent HE	FMT 15 capsules vs. SOC Enema (90 mL) vs. SOC	1 donor rich in Lachnospiraceae and Ruminococcaceae	Less SAEs in antibiotics + FMT Group.	Beta-lactamase and vancomycin-resistance reduction after FMT, regardless of the mode of administration. No difference in infections.
Bajaj J. 2019 [78]	Several	20	Cirrhotic outpatients with recurrent HE with MELD < 17	FMT capsules vs. placebo	Not specified	Reduction, at 5 months of number of total HE episodes: 6 vs. 1 and in how many patients (3 vs. 1).	An increase in relative abundance of Lachnospiraceae and Ruminococ caceae. Significant reduction of IL-6. Reduction in total primary BAs and an increase in secondary BAs and secondary/primary BA ratio. No significant changes in MELD.
Chauhan A. 2020 [84]	HBV	29	HBeAg-positive on oral antivirals ≥1 year irrespective of serum levels of HBV-DNA or AST/ALT	In duodenum; 30 g of fresh stool, diluted in 150 mL of saline ×6 cycles at 4 weeks interval	A single healthy donor	Two patients in FMT arm had HBeAg clearance 16.7% vs. 0%.	No achieved HBsAg clearance. DNA became negative faster (25% negative in 6 months). No differences in ALT 6 patients (42.8%) minor adverse events and 1 serious (abdominal pain requiring hospitalization).
Ren YD, 2017 [83]	HBV	18	Persistently positive for HBeAg following >3 years of antiviral; HBV DNA level of <10,000 IU/mL and ALT <80 U/L	FMT to duodenum every 4 weeks until HBeAg clearance was achieved vs. placebo.	Healthy donors.	HBeAg titre declined gradually after each round of FMT;	No HBeAg seroconversion No significant adverse events.

Abbreviations: PSC: Primary sclerosing cholangitis, UC: Ulcerative colitis, CD: Crohn disease, UDCA: ursodeoxycholic acid, FMT: faecal microbiota transplantation, ALP: alkaline phosphatase, OUT: Operational Taxonomic Unit, AUD: Alcohol use disorders, MELD: Model for End-stage Liver Disease, QOL: quality of life, EtG: ethyl glucuronide, CFU: Colony-forming unit, SCFA: short-chain fatty acids, TIPS: Transjugular intrahepatic portosystemic shunt, IL-6: Interleukin 6, LBP: Lypopolysaccharide binding protein, SOC: standard of care, SAE: serious adverse effects, BA: bile acids, HBV: Hepatitis B virus, HBeAg: hepatitis B virus e-antigen , AST: aspartate amino transferase , ALT: alanine amino transferase.