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Difficulty: MediumInfectious Diseases

A 68-year-old man is evaluated in the hospital on the third day of his admission for community-acquired pneumonia. He originally presented with a 3-day history of fever, productive cough, and shortness of breath. Chest radiography on admission showed a left lower lobe consolidation. He was empirically started on intravenous ceftriaxone and azithromycin. Today, he reports feeling much better and his cough has improved. He has been afebrile for the past 24 hours. His temperature is 37.1°C (98.8°F), blood pressure is 126/82 mm Hg, heart rate is 78/min, and respirations are 16/min. Pulse oximetry is 96% on ambient air. The patient is tolerating a regular diet. Blood cultures obtained on admission are sterile. Sputum culture has grown heavy *Streptococcus pneumoniae*. Susceptibility testing reveals the isolate is sensitive to penicillin, amoxicillin, ceftriaxone, levofloxacin, and vancomycin. Which of the following is the most appropriate next step in management?

  1. Switch to oral amoxicillinAnswer
  2. B
    Switch to oral amoxicillin-clavulanate
  3. C
    Switch to oral levofloxacin
  4. D
    Continue intravenous ceftriaxone and discontinue azithromycin
  5. E
    Continue intravenous ceftriaxone and intravenous azithromycin

Answer

Switch to oral amoxicillin
The correct answer is to switch to oral amoxicillin. This patient was admitted with community-acquired pneumonia and appropriately started on an empiric regimen of intravenous ceftriaxone and azithromycin. By hospital day 3, he has met the criteria for clinical stability (afebrile, normal hemodynamics, tolerating oral intake) and is a candidate for transition to oral therapy. Sputum cultures have identified Streptococcus pneumoniae, a typical bacterial pathogen, rendering continued atypical coverage with azithromycin unnecessary. Furthermore, the isolate is sensitive to penicillin. According to the principles of antimicrobial stewardship, antibiotic therapy should be de-escalated to the narrowest effective agent. Oral amoxicillin is the targeted, narrow-spectrum drug of choice for penicillin-susceptible S. pneumoniae.

Step-by-Step Solution

1
Assess the patient's clinical stability for an intravenous-to-oral transition.
The patient is afebrile for 24 hours, hemodynamically stable, has a normal respiratory rate and oxygen saturation, and is tolerating a regular diet.
Patients hospitalized with community-acquired pneumonia should be transitioned to oral antibiotics as soon as they achieve clinical stability and can safely absorb oral medications, in order to facilitate early discharge and reduce catheter-related complications.
2
Evaluate the definitive microbiology and susceptibility results.
Sputum culture confirms an infection by Streptococcus pneumoniae that is fully sensitive to penicillin and amoxicillin.
Empiric broad-spectrum therapy must be de-escalated to a targeted regimen once the causative pathogen and its susceptibility profile are identified.
3
Select the most appropriate targeted oral antibiotic based on stewardship principles.
Oral amoxicillin is the optimal choice.
Amoxicillin provides excellent, narrow-spectrum coverage for penicillin-susceptible S. pneumoniae. Broad-spectrum agents or beta-lactamase inhibitors are unnecessary and inappropriate.

Key Concept

Patients hospitalized for community-acquired pneumonia should be transitioned from empirical intravenous therapy to targeted, narrow-spectrum oral antibiotics once they demonstrate clinical stability and a susceptible pathogen is identified.
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Topics

Infectious Diseases

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