Causative agents and outcome of spontaneous bacterial peritonitis in cirrhotic patients: community-acquired versus nosocomial infections

BACKGROUND: Spontaneous bacterial peritonitis (SBP) is a serious complication and common cause of death in patients with liver cirrhosis. This study was conducted to compare the microbiological characteristics, drug resistance, and treatment outcomes for nosocomial SBP and community-acquired SBP. METHODS: A retrospective study was performed on 334 patients with culture-positive SBP at Beijing Youan Hospital, China, between January 2012 and December 2016. The medical records for these patients were reviewed, and their clinical and laboratory data were analyzed. RESULTS: A total of 155 (46.4%) patients with nosocomial SBP and 179 (53.6%) with community-acquired SBP were included in this study. From the patients’ ascitic fluids, 334 pathogenic strains, including 178 Gram-negative bacterial strains, 138 Gram-positive bacterial strains and 18 other microbial strains were isolated. E. coli was the major pathogen (24.3%), followed by Klebsiella pneumoniae (12.0%) and Enterococcus faecium (10.5%). The proportion of Enterococcus was significantly higher in the patients with nosocomial SBP (6.1% vs. 27.7%, P < 0.001) than in the patients with community-acquired SBP. The main pathogens isolated from the nosocomial infections were significantly more resistant to the first-line recommended drug. Compared with community-acquired SBP, nosocomial SBP had a poorer outcome (36.8% vs. 24.6%; P = 0.016). The independent predictors for 30-day mortality included nosocomial infection, Child-Pugh classification, hepatocellular carcinoma, renal failure and hepatic encephalopathy. CONCLUSION: Gram-negative bacteria were the major pathogens involved in SBP in the cirrhotic patients. The strains isolated from the patients with nosocomial SBP displayed higher drug resistance than those isolated from patients with community-acquired SBP. Compared with community-acquired SBP, nosocomial SBP had a poorer outcome. When choosing drug treatments, the acquisition site of infection and the local epidemiological situation should be taken into account.