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Difficulty: MediumGastroenterology and Hepatology

During morning rounds, the care team reviews the chart of a 71-year-old woman who is currently receiving inpatient treatment for acute ascending cholangitis. She was admitted three days ago with a temperature of 39.2°C (102.6°F), severe right upper quadrant pain, and scleral icterus. On the day of admission, blood cultures were drawn, and she was started on empiric intravenous piperacillin-tazobactam. The following day, she underwent an urgent endoscopic retrograde cholangiopancreatography (ERCP), during which a 12-mm common bile duct stone was successfully extracted, restoring normal biliary flow. Today, the patient reports feeling significantly better and is tolerating a liquid diet. Her vital signs are a temperature of 37.0°C (98.6°F), blood pressure of 122/76 mm Hg, and pulse of 78/min. Laboratory studies show her leukocyte count has normalized to 7,500/mm³. The microbiology laboratory reports that the admission blood cultures are positive for *Escherichia coli*. The susceptibility panel confirms the isolate is resistant to ampicillin but highly susceptible to ceftriaxone, ciprofloxacin, and piperacillin-tazobactam. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

  1. Transition to intravenous ceftriaxoneAnswer
  2. B
    Continue intravenous piperacillin-tazobactam
  3. C
    Add intravenous metronidazole to the current regimen
  4. D
    Add intravenous vancomycin to the current regimen
  5. E
    Discontinue all antimicrobial therapy

Answer

Transition to intravenous ceftriaxone
The correct action is to transition to intravenous ceftriaxone. This patient presented with acute ascending cholangitis and appropriately received broad-spectrum empiric therapy (piperacillin-tazobactam) along with definitive source control (ERCP with stone extraction). Once clinical improvement is noted and definitive culture and susceptibility data become available, a core principle of antimicrobial stewardship is to de-escalate to the most targeted, narrow-spectrum agent that is effective against the isolated organism. Because the blood cultures grew *E. coli* that is highly susceptible to ceftriaxone, continuing the broader piperacillin-tazobactam is unnecessary and inappropriate. Targeted therapy provides excellent efficacy while minimizing the risk of multidrug-resistant organism colonization.

Step-by-Step Solution

1
Evaluate the patient's current clinical status and interventions.
The patient is afebrile, hemodynamically stable, and has achieved definitive source control via ERCP.
Establishing clinical stability confirms that the current treatment trajectory is successful and safe for modification.
2
Analyze the microbiology and susceptibility data.
Blood cultures isolate E. coli that is susceptible to ceftriaxone, a narrower-spectrum agent than the empiric piperacillin-tazobactam.
Objective culture data provides the foundation for transitioning from empiric to targeted therapy.
3
Apply the principles of antimicrobial stewardship.
Piperacillin-tazobactam is discontinued in favor of ceftriaxone.
De-escalating to the narrowest effective agent minimizes the risk of resistance and secondary infections like Clostridioides difficile.

Key Concept

Antimicrobial Stewardship: De-escalation of antibiotics in acute cholangitis following source control and culture susceptibility results.
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Topics

Gastroenterology and Hepatology

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