A 68-year-old man is evaluated in the hospital on the third day of admission for acute ascending cholangitis. He initially presented with a 2-day history of right upper quadrant abdominal pain, fever, and jaundice. On admission, his temperature was 39.2°C (102.6°F) and blood pressure was 98/60 mm Hg. Laboratory studies showed a leukocyte count of 16,500/mm³, total bilirubin of 4.2 mg/dL, and alkaline phosphatase of 450 U/L.
He was empirically started on intravenous piperacillin-tazobactam and received aggressive fluid resuscitation. Within 12 hours of admission, he underwent urgent endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and extraction of a common bile duct stone.
Today, the patient feels much better. His temperature is 37.1°C (98.8°F), blood pressure is 122/78 mm Hg, and pulse is 78/min. His abdominal examination shows mild right upper quadrant tenderness without rebound or guarding.
Blood cultures drawn on admission are now growing *Escherichia coli*. The susceptibility report is as follows:
| Antibiotic | Susceptibility |
|---|---|
| Ampicillin | Resistant |
| Ciprofloxacin | Resistant |
| Ceftriaxone | Susceptible |
| Piperacillin-tazobactam | Susceptible |
| Meropenem | Susceptible |
Based on these results, which of the following is the most appropriate next step in the management of this patient's antibiotic therapy?
- Discontinue piperacillin-tazobactam and start intravenous ceftriaxoneCevap
- BContinue intravenous piperacillin-tazobactam
- CDiscontinue piperacillin-tazobactam and start oral ciprofloxacin
- DDiscontinue piperacillin-tazobactam and start intravenous meropenem
- EDiscontinue all antibiotics immediately