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Difficulty: MediumGastroenterology and Hepatology

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?

  1. Transition to intravenous ceftriaxoneAnswer
  2. B
    Continue intravenous piperacillin-tazobactam
  3. C
    Add intravenous vancomycin
  4. D
    Transition to oral amoxicillin
  5. E
    Discontinue all antibiotic therapy

Answer

Transition to intravenous ceftriaxone
The correct action is to de-escalate antibiotic therapy. This patient presented with acute ascending cholangitis and appropriately received initial broad-spectrum empiric antibiotics (piperacillin-tazobactam) alongside definitive source control (ERCP with sphincterotomy). Once blood culture and susceptibility data reveal a specific pathogen (Escherichia coli) sensitive to narrower-spectrum agents like ceftriaxone, the standard of care dictates de-escalation. Ceftriaxone provides targeted, effective coverage for the identified organism, achieves high biliary concentrations, and minimizes collateral damage to the host microbiome.

Step-by-Step Solution

1
Identify the primary diagnosis and initial interventions.
The patient presented with acute ascending cholangitis complicated by sepsis (hypotension, tachycardia) and was appropriately treated with ERCP for source control along with empiric broad-spectrum antibiotics.
Establishing the clinical timeline confirms that source control (biliary drainage) was successfully completed.
2
Analyze the microbiological data.
Blood cultures grew Escherichia coli sensitive to ceftriaxone, ciprofloxacin, and TMP-SMX, but resistant to amoxicillin.
Culture and sensitivity results must be used to guide the transition from empiric to definitive targeted therapy.
3
Determine the most appropriate definitive antibiotic strategy.
De-escalate from piperacillin-tazobactam to ceftriaxone.
Antibiotic stewardship principles dictate using the most narrow-spectrum, effective agent available once susceptibilities are known to minimize resistance and adverse effects.

Key Concept

Antibiotic de-escalation in acute cholangitis after source control
Estimated Time:1m 0s
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Topics

Gastroenterology and Hepatology

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