A 72-year-old woman is admitted to the hospital with a 2-day history of fever, severe right upper quadrant abdominal pain, and dark urine. Her temperature is 39.2°C (102.6°F), blood pressure is 94/60 mmHg, and pulse is 112/min. Physical examination reveals scleral icterus and marked right upper quadrant tenderness without rebound or guarding. Laboratory studies show a leukocyte count of 18,500/mm³ and a total bilirubin of 6.2 mg/dL. Abdominal ultrasound demonstrates a dilated common bile duct with an echogenic focus and acoustic shadowing. She is resuscitated with intravenous fluids and empirically started on intravenous piperacillin-tazobactam. An urgent endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy is performed, successfully removing a common bile duct stone and establishing biliary drainage. Two sets of blood cultures drawn upon admission subsequently grow *Escherichia coli*. Susceptibility testing reveals the organism is sensitive to ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole, but resistant to amoxicillin. On hospital day 3, the patient is afebrile, hemodynamically stable, and her leukocytosis has resolved. Which of the following is the most appropriate next step in management regarding her antibiotic therapy?
- Transition to intravenous ceftriaxoneCevap
- BContinue intravenous piperacillin-tazobactam
- CAdd intravenous vancomycin
- DTransition to oral amoxicillin
- EDiscontinue all antibiotic therapy