Impact of Bacteria Types on the Clinical Outcomes of Spontaneous Bacterial Peritonitis

Background and Aims Cirrhotic patients presenting with spontaneous bacterial peritonitis (SBP) have elevated risk of short-term mortality. While high Model for End-Stage Liver Disease-Sodium score (MELD-Na) and ascites culture yielding multi-drug resistance (MDR) bacteria are well established risk factors for further aggravating mortality, the impact of individual, causative microorganisms and their respective pathogenesis have not been previously investigated. Methods This is a retrospective study of 267 cirrhotic patients at two tertiary care hospitals undergoing paracentesis from January 2015 to January 2021 who presented with ascitic PMN count > 250 cells / mm 3 . The primary outcome was SBP progression defined as death or liver transplantation within 1-month of paracentesis stratified by microorganism type. Results Of 267 patients with SBP, the ascitic culture yielded causative microorganism in 88 cases [median age 57 years (IQR 52–64)]; 68% male; median MELD-Na 29 (IQR 23–35). The microbes isolated were E. coli (33%), Streptococcus (15%), Klebsiella (13%), Enterococcus (13%), Staphylococcus (9%) and others (18%); 41% were MDR. Cumulative incidence of SBP progression within 1-month was 91% (95% CI 67–100) for Klebsiella , 59% (95% CI 42–76) for E. coli , and 16% (95% CI 4–51) for Streptococcus . After adjusting for MELD-Na and MDR, risk of SBP progression remained elevated for Klebsiella (HR 2.07; 95% CI 0.98–4.24; p -value = 0.06) and decreased for Streptococcus (HR 0.28; 95% CI 0.06–1.21; p -value = 0.09) compared to all other bacteria. Conclusion Our study found Klebsiella -associated SBP had worse clinical outcomes while Streptococcus -associated SBP had the most favorable outcomes after accounting for MDR and MELD-Na. Thus, identification of the causative microorganism is crucial not only for optimizing the treatment but for prognostication.