Pathogen distribution, antimicrobial resistance, and gut microbiota dysbiosis in patients with cirrhosis complicated by infection in northwestern China.

INTRODUCTION: Infection is a major complication of liver cirrhosis and is associated with substantial morbidity and mortality. However, regional data on pathogen distribution, antimicrobial resistance patterns, and gut microbiota and metabolic alterations among cirrhotic patients with infection in Northwest China remain limited. This study aimed to characterize these features and explore the associations between gut microbiota, short-chain fatty acids (SCFAs), and clinical inflammatory indices in cirrhotic patients with infection. METHODS: We retrospectively analyzed 4,425 hospitalized patients with liver cirrhosis between January 2017 and October 2025, including 1,056 patients with concurrent infections, to characterize pathogen distribution and antimicrobial susceptibility patterns. In addition, a prospectively enrolled subgroup of 86 participants was analyzed for gut microbiota composition and fecal SCFA levels. Gut microbiota was characterized using 16S rRNA gene sequencing, and fecal SCFA concentrations were determined by appropriate analytical methods. The discriminatory ability of inflammatory indices, including the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and systemic immune-inflammation index (SII), was assessed using receiver operating characteristic (ROC) curve analysis. RESULTS: The most frequently isolated Gram-negative bacteria were Escherichia coli (22.32%), Klebsiella pneumoniae (13.27%), Acinetobacter baumannii (7.36%), and Pseudomonas aeruginosa (5.07%), while the predominant Gram-positive bacteria were Enterococcus faecium (9.17%) and Staphylococcus aureus (6.39%). Fungi accounted for 4.58% of isolates. Antimicrobial susceptibility testing revealed substantial resistance to multiple antibiotics among the major pathogens. ROC analysis showed that NLR and MLR had high discriminative ability for distinguishing infected from non-infected cirrhotic patients, with AUCs of 0.9447 and 0.9083, respectively, while SII showed comparatively lower discriminative ability. In the microbiome subgroup, patients with spontaneous bacterial peritonitis (LCIF-SBP) exhibited distinct gut microbiota profiles compared with cirrhotic patients without infection (LCNOIF) and healthy controls. SCFA-producing genera, including Bifidobacterium and Faecalibacterium, were reduced, whereas Escherichia-Shigella was enriched. Fecal butyrate levels were significantly lower in the LCIF-SBP group than in the LCNOIF group. Correlation analysis showed that Escherichia-Shigella was negatively correlated with fecal butyrate levels and positively correlated with MLR. DISCUSSION: Our findings provide regional data on pathogen distribution, antimicrobial resistance, gut microbiota alterations, and SCFA profiles among cirrhotic patients with infection in Northwest China. The observed associations between gut microbial dysbiosis, reduced butyrate levels, and inflammatory indices highlight potential links between intestinal microbial alterations and infection in cirrhosis. Further longitudinal, multicenter, and mechanistic studies are needed to determine whether these microbiota and metabolic alterations contribute causally to infection susceptibility and to evaluate their potential clinical relevance.