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Difficulty: HardGastroenterology and Hepatology

A 58-year-old man with a history of type 2 diabetes mellitus is evaluated in the inpatient ward. He was admitted two days ago with a three-day history of high fever, chills, and severe right upper quadrant abdominal pain. At admission, his temperature was 39.4°C (102.9°F). A contrast-enhanced abdominal CT scan revealed a 6.5-cm fluid-filled collection with peripheral enhancement in the right hepatic lobe.

The patient underwent prompt ultrasound-guided percutaneous drain placement. Empiric antimicrobial therapy with intravenous piperacillin-tazobactam was initiated.

Currently, on hospital day 3, the patient reports significant symptomatic improvement. His temperature is 37.2°C (99.0°F), and his vital signs are stable. The percutaneous drain is producing minimal serosanguinous output.

Microbiology results for both blood and abscess fluid cultures have returned, as shown below:

Organism*Klebsiella pneumoniae*
AmpicillinResistant
CeftriaxoneSusceptible
CiprofloxacinSusceptible
MeropenemSusceptible
Piperacillin-tazobactamSusceptible

Based on these results, which of the following is the most appropriate next step in the pharmacologic management of this patient?

  1. A
    Continue intravenous piperacillin-tazobactam without modification
  2. B
    Transition to intravenous meropenem monotherapy
  3. Transition to intravenous ceftriaxone monotherapyAnswer
  4. D
    Transition to intravenous ceftriaxone and intravenous metronidazole
  5. E
    Transition to intravenous vancomycin and intravenous ciprofloxacin

Answer

The correct approach is to transition to intravenous ceftriaxone monotherapy.
The correct next step is to transition to a targeted, narrower-spectrum agent based on the culture results. The patient has a monomicrobial *Klebsiella pneumoniae* pyogenic liver abscess. With the isolate demonstrating susceptibility to ceftriaxone, transitioning to intravenous ceftriaxone monotherapy effectively treats the infection while strictly adhering to the principles of antimicrobial stewardship. There is no need to continue exceptionally broad Gram-negative or anaerobic coverage once a susceptible monomicrobial aerobic/facultative organism is identified.

Step-by-Step Solution

1
Evaluate the clinical scenario and recent interventions.
The patient has a pyogenic liver abscess that has been adequately source-controlled via percutaneous drainage, and he is showing clinical improvement on empiric piperacillin-tazobactam.
To determine the patient's current stability and the necessity of ongoing interventions.
2
Analyze the microbiology culture and susceptibility data.
The infection is caused by a monomicrobial Klebsiella pneumoniae bacteremia and abscess, which is susceptible to ceftriaxone, ciprofloxacin, meropenem, and piperacillin-tazobactam.
To guide the selection of targeted, definitive antimicrobial therapy.
3
Apply the principles of antimicrobial stewardship.
De-escalate the broad-spectrum empiric regimen (piperacillin-tazobactam) to the safest, narrowest-spectrum effective agent (ceftriaxone).
To effectively eradicate the known pathogen while minimizing collateral damage to normal flora, reducing the risk of Clostridioides difficile infection, and preventing the emergence of antimicrobial resistance.

Key Concept

Empiric broad-spectrum antimicrobial therapy must be de-escalated to a targeted, narrower-spectrum agent once definitive culture and susceptibility results are available, in accordance with antimicrobial stewardship principles.
Estimated Time:1m 15s
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Topics

Gastroenterology and Hepatology

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