Spontaneous bacterial peritonitis (SBP) in patients with cirrhosis is typically caused by gram-negative bacteria. However, the number of SBP cases due to gram-positive bacteria is steadily increasing. To date, little is known about the predictive factors involved in SBP infections. We performed a retrospective cohort study of patients (>18 years) with SBP due to gram-positive and-negative bacteria who were enrolled from January 2006 to December 2013 at Severance Hospital in Seoul, Korea where the incidences of hepatitis B virus associated chronic liver disease, cirrhosis, and hepatocellular carcinoma are high. Only the 1st SBP episode for each patient within the study period was included in our analysis. We identified 77 patients with cirrhosis and SBP. Of these, 27 patients (35%) had gram-positive bacterial infections and 50 patients (65%) had gram-negative bacterial infections. Our univariate analysis revealed that an early stage of cirrhosis (P = 0.004), lower creatinine level (P = 0.011), lower Sequential Organ Failure Assessment (SOFA) score (P = 0.001), lower Model for End-Stage Liver Disease score (P = 0.005), and use of systemic antibiotics within 30 days before SBP diagnosis (P = 0.03) were significantly associated with gram-positive bacterial infections. Our multivariate analysis indicated that the use of systemic antibiotics within 30 days before SBP diagnosis (odds ratio, 3.94; 95% CI, 1.11-13.96; P = 0.033) and a lower SOFA score (odds ratio, 0.56; 95% CI, 0.37-0.86; P = 0.007) were independent predictive factors of SBP caused by gram-positive bacterial infections in patients with cirrhosis. However, we did not observe a statistically significant difference in the 28-day mortality between the gram-positive and-negative bacterial infection groups (40.7% vs 46.0%, respectively; P = 0.407). In this study, the incidence rate of SBP caused by gram-positive bacteria in patients with cirrhosis was similar to the rates reported in recently published studies. Furthermore, the use of systemic antibiotics within 30 days before SBP diagnosis and a lower SOFA score were significantly associated with SBP caused by gram-positive bacteria in patients with cirrhosis.
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