Secondary Bacterial Peritonitis Due to an Inadequately Treated Renal Abscess

Secondary bacterial peritonitis is a life-threatening disease requiring early distinction from spontaneous bacterial peritonitis due to shared features such as fever, leukocytosis, and abdominal pain. Despite appropriate antibiotic therapy, persistent fever, leukocytosis, and culture-positive fluid should always prompt further investigation for a secondary source of infection. The authors present a rare case of a patient with cirrhosis who had an untreated perinephric abscess and developed antibiotic-resistant peritonitis, raising concerns of secondary bacterial peritonitis arising from the abscess. The patient presented to the emergency department with malaise, nausea, and vomiting in the context of a recent admission 2 months prior for a urinary tract infection caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, which is sensitive to ertapenem. This was complicated by the development of multiple renal abscesses. At the time, the patient received a percutaneous drain in his largest renal abscess and was discharged with an outpatient ertapenem infusion scheduled 1 month later, but he was unable to follow up. Despite adequate antibiotic therapy, peritoneal drainage demonstrated persistent culture-positive fluid and elevated neutrophils, raising suspicion of a secondary source of peritonitis that ultimately required surgical intervention. This case emphasises the importance of early suspicion of a secondary source of peritonitis in patients who demonstrate persistent fever, leukocytosis, and culture-positive peritoneal fluid despite adequate antibiotic therapy, and a difference in management for spontaneous bacterial peritonitis versus secondary peritonitis.