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Difficulty: MediumInfectious Diseases

During morning rounds, the attending physician reviews the progress of a 71-year-old man who was admitted 4 days ago with shortness of breath, pleuritic chest pain, and a left-sided pulmonary consolidation. The patient was diagnosed with severe community-acquired pneumonia and started on an empiric regimen of intravenous ceftriaxone and azithromycin. Blood cultures collected in the emergency department have yielded *Streptococcus pneumoniae*. Susceptibility testing demonstrates that the organism is highly sensitive to penicillin, amoxicillin, and moxifloxacin, but exhibits resistance to macrolides. The patient has shown marked clinical improvement; he is currently breathing comfortably on ambient air, successfully eating solid meals, and has recorded no temperature elevations for the past 24 hours. His current vital signs show a temperature of 37.0 °C (98.6 °F), blood pressure of 132/82 mm Hg, heart rate of 74/min, and respiratory rate of 14/min. Based on the culture results and clinical status, which of the following is the most appropriate pharmacological management?

  1. Discontinue current medications and prescribe an outpatient course of oral amoxicillin.Answer
  2. B
    Discontinue current medications and prescribe an outpatient course of oral moxifloxacin.
  3. C
    Discontinue current medications and prescribe an outpatient course of oral amoxicillin-clavulanate.
  4. D
    Maintain the current dose of intravenous ceftriaxone to complete a full 7-day inpatient course.
  5. E
    Add intravenous vancomycin to the current regimen until radiographic resolution is confirmed.

Answer

Discontinue current medications and prescribe an outpatient course of oral amoxicillin.
The correct decision is to transition the patient to oral amoxicillin and arrange for discharge. The patient meets all criteria for transitioning to oral antibiotics: he is hemodynamically stable, afebrile for more than 18-24 hours, has a normal respiratory rate, maintains normal oxygenation on room air, and can tolerate oral intake. Because blood cultures confirmed *Streptococcus pneumoniae* susceptible to penicillin, the principles of antimicrobial stewardship dictate narrowing the treatment spectrum. Amoxicillin is the optimal narrow-spectrum oral agent for penicillin-susceptible *S. pneumoniae*. Discharging the patient minimizes the risk of hospital-acquired complications.

Step-by-Step Solution

1
Evaluate the patient's clinical stability for transition to oral therapy.
The patient is afebrile, hemodynamically stable, breathing comfortably on room air, and tolerating an oral diet.
Patients hospitalized with pneumonia can be safely switched to oral antibiotics and discharged once they achieve clinical stability.
2
Analyze the microbiological data to tailor antimicrobial therapy.
Blood cultures grew Streptococcus pneumoniae that is susceptible to penicillin and amoxicillin, but resistant to macrolides.
Empiric broad-spectrum therapy must be de-escalated to the narrowest effective agent once culture and susceptibility results are available.
3
Select the most appropriate targeted oral antibiotic.
Oral amoxicillin is selected as the step-down therapy.
High-dose oral amoxicillin provides excellent coverage for penicillin-susceptible S. pneumoniae while minimizing collateral damage to the microbiome compared to broader agents like fluoroquinolones or amoxicillin-clavulanate.

Key Concept

Antimicrobial stewardship in community-acquired pneumonia requires transitioning clinically stable patients to targeted, narrow-spectrum oral therapy based on susceptibility data.
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Topics

Infectious Diseases

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