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Difficulty: EasyInfectious Diseases

During morning rounds on the medical ward, a physician reviews the progress of a 72-year-old male patient. The patient was admitted 72 hours ago due to fever and acute delirium secondary to a catheter-associated urinary tract infection. Upon admission, the urinary catheter was removed, and broad-spectrum empiric therapy with intravenous vancomycin and piperacillin-tazobactam was initiated. Currently, the patient is afebrile, hemodynamically stable, and eating a regular diet. His mental status has completely returned to baseline. Final culture results from both blood and urine reveal growth of *Enterococcus faecalis*. Susceptibility panels indicate the organism is sensitive to ampicillin, vancomycin, linezolid, and daptomycin. Based on the culture results and clinical improvement, which of the following is the most appropriate pharmacological intervention for this patient?

  1. Transition to oral amoxicillinAnswer
  2. B
    Continue intravenous vancomycin and piperacillin-tazobactam
  3. C
    Discontinue piperacillin-tazobactam and continue intravenous vancomycin
  4. D
    Transition to oral linezolid
  5. E
    Discontinue vancomycin and continue intravenous piperacillin-tazobactam

Answer

Transition to oral amoxicillin
The most appropriate next step is to transition the patient to oral amoxicillin. This patient has a catheter-associated urinary tract infection with secondary bacteremia that has clinically resolved following appropriate source control (catheter removal) and initial empiric antibiotics. With culture results demonstrating ampicillin-susceptible *Enterococcus faecalis*, principles of antibiotic stewardship dictate de-escalating from broad-spectrum empiric therapy to the most targeted, effective, and safe narrow-spectrum agent available. Beta-lactams (like ampicillin or amoxicillin) are superior to vancomycin for susceptible enterococci. Because the patient is clinically stable, afebrile, and tolerating a diet, an oral agent with excellent bioavailability and urinary concentration, such as amoxicillin, is the ideal definitive therapy.

Step-by-Step Solution

1
Evaluate the patient's current clinical stability.
The patient is afebrile, hemodynamically stable, back to baseline mental status, and tolerating oral intake.
Determines that the patient is a safe candidate to step down from intravenous to oral antibiotic therapy.
2
Review the microbiological culture and susceptibility data.
The causative organism is Enterococcus faecalis, which is fully susceptible to ampicillin.
Identifies the exact pathogen to transition from empiric to definitive targeted therapy.
3
Select the most appropriate definitive antibiotic agent.
Oral amoxicillin is chosen to complete the treatment course.
Principles of antibiotic stewardship dictate selecting the narrowest spectrum, most effective, and least toxic agent available. Amoxicillin fits this perfectly for susceptible E. faecalis.

Key Concept

Antibiotic de-escalation and stewardship for fully susceptible isolates
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Topics

Infectious Diseases

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