How the Gut Microbiome Affects Outcomes in Cirrhosis: A Review

Emerging evidence supports a role for gut microbiota in shaping immune and metabolic functions. In patients with cirrhosis, we know that dysbiosis is associated with adverse effects on metabolism and immunity that can lead to complications such as spontaneous bacterial peritonitis, hepatic encephalopathy, and variceal hemorrhage.

To assess the current evidence on the effects of dysbiosis on outcomes of cirrhosis, researchers conducted a review of relevant studies published through April 2015. Key findings include:

• Alterations found in the composition of enteric flora in patients with cirrhosis include elevated Enterobacter and Enterococcus and reduced Bifidobacteria. In addition, microbial and genetic diversity is lower compared with healthy patients.

• The process by which dysbiosis contributes to hepatic encephalopathy is production of ammonia and endotoxin-driven inflammation.

• The process by which dysbiosis contributes to spontaneous bacterial peritonitis is bacterial translocation, resulting from bacterial overgrowth, increased intestinal permeability, and integrity of immune surveillance mechanisms.

• The success of gut decontamination to treat cirrhosis-related events (e.g., rifaximin use in treating hepatic encephalopathy) highlights the central role of the gut microbiota in their pathogenesis.

• The possible role of probiotics in treating complications of cirrhosis such as hepatic encephalopathy is inconclusive due to substantial heterogeneity of clinical trials.