Soru

A $58$-year-old man with decompensated cirrhosis due to alcohol use disorder is evaluated on hospital day $3$ for ongoing management of spontaneous bacterial peritonitis. He initially presented with a temperature of $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), diffuse abdominal pain, and confusion. Diagnostic paracentesis on admission showed an ascitic fluid absolute neutrophil count of $850/\text{mm}^3$. Because of a history of extended-spectrum beta-lactamase (ESBL)-producing *Escherichia coli* bacteriuria $6$ months ago, he was empirically started on intravenous meropenem. Intravenous albumin ($1.5$ g/kg) was also administered on admission based on the following laboratory results:

Admission (Day 1):
Blood urea nitrogen: $34$ mg/dL
Serum creatinine: $1.5$ mg/dL
Total bilirubin: $5.2$ mg/dL

Today (Day 3), the patient is feeling much better. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), and his mental status has returned to baseline. Ascitic fluid cultures from admission have grown *Klebsiella pneumoniae*. Antimicrobial susceptibility testing is as follows:
Ampicillin: Resistant
Ceftriaxone: Susceptible
Ciprofloxacin: Susceptible
Meropenem: Susceptible
Piperacillin-tazobactam: Susceptible

Current laboratory results:
Blood urea nitrogen: $24$ mg/dL
Serum creatinine: $1.1$ mg/dL
Total bilirubin: $4.5$ mg/dL

Which of the following is the most appropriate next step in the management of this patient?