E) Start ceftriaxone intravenously

This patient with nephrotic syndrome and fever is at risk for spontaneous bacterial peritonitis (SBP) due to a combination of factors, including loss of immunoglobulins and complement in urine and ascites formation secondary to hypoalbuminemia. The ascites fluid analysis confirms SBP with a PMN count ≥ 250 cells/μL, even in the absence of organisms on Gram stain. Empiric antibiotic therapy with a third-generation cephalosporin (e.g., ceftriaxone or cefotaxime) is indicated immediately.

Answer choice A: Begin oral ciprofloxacin as prophylaxis, is incorrect. Antibiotic prophylaxis is used to prevent SBP in high-risk patients but is not appropriate for acute management.

Answer choice B: Increase the dose of prednisone, is incorrect: Prednisone is not indicated for acute infection and may worsen the immune compromise.

Answer choice C: Monitor the patient closely with serial abdominal examinations, is incorrect. Delaying treatment in a febrile patient with nephrotic syndrome and ascitic fluid PMN count ≥ 250 cells/μL is inappropriate and increases mortality risk.

Answer choice D: Perform an abdominal CT scan, is incorrect. Imaging may be considered if secondary peritonitis (e.g., perforation or abscess) is suspected, but this patient does not show signs of peritonitis such as guarding or rebound tenderness.

Key Learning Point

In patients with nephrotic syndrome and fever, prompt evaluation and empiric antibiotics for spontaneous bacterial peritonitis (SBP) are critical, even in the absence of cirrhosis.