Gut Microbiota and Infectious Complications in Advanced Chronic Liver Disease: Focus on Spontaneous Bacterial Peritonitis.

Liver cirrhosis is a chronic disease that can be complicated by episodes of decompensation such as variceal bleeding, hepatic encephalopathy, ascites, and jaundice, with subsequent increased mortality. Infections are also among the most common complications in cirrhotic patients, mostly due to a defect in immunosurveillance. Among them, one of the most frequent is spontaneous bacterial peritonitis (SBP), defined as the primary infection of ascitic fluid without other abdominal foci. SBP is mainly induced by Gram-negative bacteria living in the intestinal tract, and translocating through the intestinal barrier, which in cirrhotic patients is defective and more permeable. Moreover, in cirrhotic patients, the intestinal microbiota shows an altered composition, poor in beneficial elements and enriched in potentially pathogenic ones. This condition further promotes the development of leaky gut and increases the risk of SBP. The first-line treatment of SBP is antibiotic therapy; however, the antibiotics used have a broad spectrum of action and may adversely affect the composition of the gut microbiota, worsening dysbiosis. For this reason, the future goal is to use new therapeutic agents that act primarily on the gut microbiota, selectively modulating it, or on the intestinal barrier, reducing its permeability. In this review, we aim to describe the reciprocal relationship between gut microbiota and SBP, focusing on pathogenetic aspects but also on new future therapies.

Improved gut microbiota features after the resolution of SARS­CoV­2 infection.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2) has a tropism for the gastrointestinal tract and several studies have shown an alteration of the gut microbiota in hospitalized infected patients. However, long-term data on microbiota changes after recovery are lacking. METHODS: We enrolled 30 patients hospitalized for SARS­CoV­2-related pneumonia. Their gut microbiota was analyzed within 48 h from the admission and compared with (1) that of other patients admitted for suspected bacterial pneumonia (control group) (2) that obtained from the same subject 6 months after nasopharyngeal swab negativization. RESULTS: Gut microbiota alpha-diversity increased 6 months after the resolution of SARS-CoV-2 infection. Bacteroidetes relative abundance was higher (≈ 36.8%) in patients with SARS-CoV-2, and declined to 18.7% when SARS-CoV-2 infection resolved (p = 0.004). Conversely, Firmicutes were prevalent (≈ 75%) in controls and in samples collected after SARS-CoV-2 infection resolution (p = 0.001). Ruminococcaceae, Lachnospiraceae and Blautia increased after SARS-CoV-2 infection resolution, rebalancing the gut microbiota composition. CONCLUSION: SARS-CoV-2 infection is associated with changes in the gut microbiome, which tend to be reversed in long-term period.

Liver involvement is not associated with mortality: results from a large cohort of SARS-CoV-2-positive patients.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is frequently associated with liver test abnormalities. AIMS: To describe the evolution of liver involvement during SARS-CoV-2 infection and its effect on clinical course and mortality. METHODS: Data of 515 SARS-CoV-2-positive patients were collected at baseline and during follow-up, last evaluation or death. Stratification based on need for hospitalisation, severe disease and admission to intensive care unit (ICU) was performed. The association between liver test abnormalities (baseline and peak values) and ICU admission or death was also explored. RESULTS: Liver test abnormalities were found in 161 (31.3%) patients. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT) were increased in 20.4%, 19% and 13.6% of patients, respectively. Baseline liver test abnormalities were associated with increased risk of ICU admission (OR 2.19 [95% CI 1.24-3.89], P = 0.007) but not with mortality (OR 0.84 [95% CI 0.49-1.41], P = 0.51). Alkaline phosphatase (ALP) peak values were correlated with risk of death (OR 1.007 [95% CI 1.002-1.01], P = 0.005) along with age, multiple comorbidities, acute respiratory distress syndrome, ICU admission and C-reactive protein. Alterations of liver tests worsened within 15 days of hospitalisation; however, in patients with the longest median follow-up, the prevalence of liver test alterations decreased over time, returning to around baseline levels. CONCLUSIONS: In SARS-CoV-2-positive patients without pre-existing severe chronic liver disease, baseline liver test abnormalities are associated with the risk of ICU admission and tend to normalise over time. The ALP peak value may be predictive of a worse prognosis.