A 48-year-old man with a 15-year history of alcohol abuse presents with acute-onset jaundice, fever (38.5°C), right upper quadrant pain, and hepatomegaly. Laboratory findings: AST 380 U/L, ALT 220 U/L, ALP 280 U/L, total bilirubin 6.8 mg/dL, albumin 3.2 g/dL, INR 1.8, WBC 14,500/μL. Ultrasound shows fatty infiltration of liver and dilated intrahepatic bile ducts. Blood cultures are pending. What is the most appropriate next step in management?