Spontaneous bacterial peritonitis in adults with nephrotic syndrome: a case series and review of the literature

Spontaneous bacterial peritonitis (SBP) is a rare but serious complication in adults with nephrotic syndrome (NS). Unlike pediatric cases, its incidence in adults remains low, with fewer than 30 reported cases. Factors such as severe proteinuria, hypoalbuminemia, immunosuppressive therapy (IST), and ascitic fluid accumulation contribute to an increased risk of infection. This study aims to describe the clinical features, microbiological findings, management, and outcomes of SBP in adults with NS. We conducted a retrospective review of six adult patients diagnosed with NS and admitted to our nephrology department for SBP between January 2021 and December 2024. Clinical data, laboratory findings, microbiological cultures, imaging, treatment regimens, and outcomes were analyzed. All patients were male, with a mean age of 23 years (range: 21–33). Focal segmental glomerulosclerosis (FSGS) was the underlying renal pathology in all cases. Patients presented with abdominal pain, ascites, and fever. SBP was confirmed either by ascitic fluid analysis or presumed based on clinical and radiologic findings. Klebsiella pneumoniae was identified in one case, two cases yielded negative cultures, and in five cases ascitic fluid cultures could not be performed. All patients had active NS, and most were receiving IST. Empirical broad-spectrum antibiotics, including ceftriaxone, ciprofloxacin, metronidazole, and aminoglycosides, led to clinical resolution in all cases. Two patients experienced SBP recurrence. SBP, though rare in adult NS patients, should be suspected in those presenting with abdominal symptoms and ascites, particularly when immunosuppression and hypoalbuminemia are present. Early diagnosis and prompt empirical antibiotic therapy are essential for favorable outcomes. Further studies are needed to establish optimal preventive and therapeutic strategies in this population.