Integrated analysis of gut microbiota structure and metabolic function in patients with cirrhosis and refractory ascites

Refractory ascites is a serious complication of decompensated cirrhosis, yet its intestinal microbial and metabolic characteristics remain incompletely understood. The present study combined 16S rRNA sequencing and gas chromatography-mass spectrometry-based untargeted metabolomics to investigate the gut microbial composition and metabolite profiles of 70 patients with refractory ascites due to cirrhosis (OB group) and 70 healthy individuals (NC group). Analyses included microbial diversity evaluation, taxonomic comparison, functional prediction, metabolite screening and disease association mapping. Compared with the NC group, the OB group showed reduced α diversity and distinct β diversity patterns, with enrichment of Proteobacteria and a reduction in anaerobic and Gram-positive taxa. BugBase analysis indicated increased proportions of potentially pathogenic, biofilm-forming and oxidative stress-tolerant phenotypes. LEfSe analysis further revealed group-specific taxa, such as enrichment of Bacteroidota and Actinobacteriota in the NC group and Firmicutes-related genera including <i>Clostridium</i> and <i>Lactobacillus</i> in the OB group. Functional predictions suggested group differences in carbohydrate and lipid metabolism, membrane transport and vitamin-related pathways. Metabolomic analysis identified 2,890 altered metabolites and Kyoto Encyclopedia of Genes and Genomes enrichment highlighted an involvement in serotonergic synapse and steroid hormone biosynthesis. Receiver operator characteristic curve analysis revealed a good discriminatory performance (area under the curve >0.93) for 10 selected metabolites. Several of these metabolites, including L-tryptophan and hypoxanthine, were further linked to inflammatory, neurodegenerative and neoplastic diseases. In conclusion, patients with refractory ascites exhibited notable structural and functional alterations in gut microbiota and metabolism. These findings provide insights into the gut-liver axis in cirrhosis and may inform future research on microbial or metabolic biomarkers.