Spontaneous Bacterial Peritonitis in an Adult Patient with Minimal Change Disease

BACKGROUND Pediatric patients with nephrotic syndrome have a high risk of developing spontaneous bacterial peritonitis (SBP). However, SBP in adults with nephrotic syndrome is very rare. We report a case of SBP induced by Escherichia coli in a 60-year-old male patient on immunosuppressive therapy for the treatment of minimal change disease (MCD). CASE REPORT The patient was hospitalized with abdominal pain and generalized edema that had lasted for 2 weeks. The patient first started treatment with high-dose oral prednisolone after being diagnosed with MCD 6 months ago. Complete remission of nephrotic syndrome was not achieved even after 5 months of treatment. Thus, the treatment was changed to combination therapy with cyclosporine and low-dose prednisolone. At the time of admission, leukocytosis, hypoalbuminemia, decreased serum immunoglobulin G (IgG), azotemia, and nephrotic-range proteinuria were observed. Ascitic fluid analysis showed a leukocyte count of 4960/μL (neutrophils 90%). On the suspicion of SBP associated with MCD, intravenous administration of empirical cefotaxime and supportive therapy were initiated; however, symptoms of peritonitis persisted. Extended-spectrum beta-lactamase-negative E. coli was found in ascites cultures. Laparoscopy-assisted peritoneal biopsy revealed no evidence of fungal infection; however, chronic inflammation without granuloma formation was noted. Afterward, cefotaxime was changed to piperacillin-tazobactam. After 4 weeks of antibacterial therapy, the peritonitis was cured and renal function was improved. CONCLUSIONS Adult patients with steroid-resistant MCD accompanied by refractory ascites, severe hypoalbuminemia, and marked reduction in serum IgG are at a high risk of subsequent SBP and require careful monitoring.