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Difficulty: HardGastroenterology and Hepatology

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:

AntibioticSusceptibility
AmpicillinResistant
CiprofloxacinResistant
CeftriaxoneSusceptible
Piperacillin-tazobactamSusceptible
MeropenemSusceptible

Based on these results, which of the following is the most appropriate next step in the management of this patient's antibiotic therapy?

  1. Discontinue piperacillin-tazobactam and start intravenous ceftriaxoneAnswer
  2. B
    Continue intravenous piperacillin-tazobactam
  3. C
    Discontinue piperacillin-tazobactam and start oral ciprofloxacin
  4. D
    Discontinue piperacillin-tazobactam and start intravenous meropenem
  5. E
    Discontinue all antibiotics immediately

Answer

Discontinue piperacillin-tazobactam and start intravenous ceftriaxone
The most appropriate next step is to de-escalate the antibiotic regimen to intravenous ceftriaxone. This patient presented with acute ascending cholangitis and sepsis, for which empiric broad-spectrum coverage with piperacillin-tazobactam was correctly initiated. However, once blood cultures have identified a specific pathogen (*E. coli*) and susceptibilities are known, the principles of antimicrobial stewardship mandate de-escalating to a narrower-spectrum, targeted agent. Ceftriaxone is highly active against this isolate and has excellent biliary penetration, making it the ideal choice for completing the treatment course after successful source control via ERCP.

Step-by-Step Solution

1
Evaluate the patient's clinical progress and interventions.
The patient had acute ascending cholangitis, achieved effective source control via ERCP, and is now clinically stable and afebrile.
Determining clinical stability is necessary before modifying an empiric antibiotic regimen.
2
Analyze the blood culture and susceptibility results.
The infection is driven by an *E. coli* strain that is susceptible to ceftriaxone, piperacillin-tazobactam, and meropenem, but resistant to ampicillin and ciprofloxacin.
Culture data dictates the transition from empiric to definitive targeted therapy.
3
Apply the principles of antimicrobial stewardship.
The regimen should be de-escalated from the broad-spectrum piperacillin-tazobactam to the narrower-spectrum ceftriaxone.
De-escalation minimizes collateral damage to the patient's microbiome and reduces the risk of generating multidrug-resistant organisms.

Key Concept

Antibiotic de-escalation in acute cholangitis following source control.
Estimated Time:1m 30s
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Topics

Gastroenterology and Hepatology

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