Review Question - QID 109786

A 56-year-old man presents to the emergency department for progressively worsening fatigue, malaise, fever, and abdominal pain. His symptoms began approximately 1 week ago and he has noticed episodes of diarrhea. He recently started melatonin and magnesium supplementation in hopes of improving his sleep. Medical history is significant for alcohol use disorder that required multiple hospital admissions for the management of acute pancreatitis and cirrhosis. He occasionally injects heroin intravenously. His temperature is 100°F (37.8°C), blood pressure is 105/70 mmHg, pulse is 92/min, and respirations are 17/min. Physical examination is significant for scleral icterus, hepatomegaly, ascites, and diffuse abdominal tenderness. Laboratory testing is significant for leukocytosis and metabolic acidosis. A paracentesis is performed and he is admitted into the hospital to receive intravenous cefotaxime and albumin. The ascitic fluid analysis demonstrates a polymorphonuclear cell count of 280 cells/mm^3, serum ascites-albumin gradient of 1.3 g/dL, and culture positive for Escherichia coli sensitive to cefotaxime and ceftriaxone. On hospital day 2, the nurse reports that the patient is oliguric in the setting of constant fluid intake. Physical examination is unchanged. Laboratory testing is significant for serum sodium of 131 mEq/L and creatinine of 1.8 mg/dL (it was 0.9 mg/dL on admission). Urine studies are significant for a low urine sodium level, without evidence of blood or protein. Since hospital admission, he has not been started on any new medications. Which of the following is the most appropriate treatment option for this patient?