Spontaneous Bacterial Peritonitis Beyond the Usual Suspects: Case Series of Salmonella and Brucella With Comprehensive Literature Review.

While Escherichia coli, Streptococcus, and Klebsiella species traditionally account for most cases of spontaneous bacterial peritonitis (SBP), atypical pathogens can be found. Salmonella, typically known for causing gastroenteritis, rarely manifests as SBP, while Brucella, a zoonotic pathogen, presents a unique challenge in the context of peritoneal infection. In this report, we present two cases of SBP caused by these atypical organisms. The first case involved a 58-year-old female with a history of hepatitis C-related chronic liver disease and cryoglobulinemic vasculitis, who presented with SBP and hepatorenal syndrome-associated acute kidney injury. Salmonella was identified in both ascitic fluid and blood cultures, but despite appropriate treatment, the patient experienced a fatal deterioration. The second case features a 52-year-old male with type 2 diabetes mellitus and newly diagnosed schistosomiasis, who presented with findings of decompensated liver cirrhosis and SBP. Brucella was isolated from ascitic fluid cultures, and the patient responded well to treatment. We aim to highlight the need for early recognition of atypical causes of SBP to improve management and outcomes.