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Difficulty: MediumInfectious Diseases

A 65-year-old man is evaluated in the hospital on day 3 of admission for community-acquired pneumonia. On presentation, he had a fever, productive cough, and a right lower lobe consolidation on chest radiography. Blood and sputum cultures were obtained, and he was empirically started on intravenous ceftriaxone and oral azithromycin. Today, both blood and sputum cultures are growing Streptococcus pneumoniae. Antimicrobial susceptibility testing reveals the isolate is susceptible to penicillin, amoxicillin, ceftriaxone, and levofloxacin. The patient has improved significantly; his fever has resolved, his cough is much improved, and he is comfortably breathing room air with an oxygen saturation of 97%. He is tolerating a regular diet and mobilizing well. His temperature is 37.1°C (98.8°F), blood pressure is 128/82 mm Hg, pulse is 76/min, and respiratory rate is 16/min. Which of the following is the most appropriate next step in management?

  1. A
    Discontinue oral azithromycin and continue intravenous ceftriaxone
  2. B
    Discontinue the current antibiotics and transition to oral levofloxacin
  3. Discontinue the current antibiotics and transition to oral amoxicillinAnswer
  4. D
    Discontinue the current antibiotics and transition to oral amoxicillin-clavulanate
  5. E
    Continue both intravenous ceftriaxone and oral azithromycin

Answer

Discontinue the current antibiotics and transition to oral amoxicillin
The correct approach for this patient is to discontinue the current empiric antibiotics and begin a targeted, narrow-spectrum oral agent. The patient was admitted with community-acquired pneumonia and initially treated with a standard empiric regimen of ceftriaxone and azithromycin. Blood and sputum cultures have now grown Streptococcus pneumoniae that is susceptible to penicillin and amoxicillin. According to antimicrobial stewardship principles, patients who are clinically stable (afebrile, normalizing vital signs) and able to tolerate oral intake should be transitioned from intravenous to oral therapy. Furthermore, therapy should be narrowed to the most targeted effective agent. Oral amoxicillin is the drug of choice for step-down therapy in penicillin-susceptible Streptococcus pneumoniae infections. Discontinuing azithromycin is also required because empiric atypical coverage is no longer needed once a typical bacterial pathogen is identified.

Step-by-Step Solution

1
Evaluate the patient's clinical trajectory and hemodynamic status.
The patient is afebrile, hemodynamically stable, has improving respiratory symptoms, and is tolerating an oral diet.
To determine if the patient meets the criteria for transitioning from intravenous to oral antimicrobial therapy.
2
Review the microbiological culture and susceptibility results.
Cultures confirm Streptococcus pneumoniae that is susceptible to narrow-spectrum beta-lactams (penicillin, amoxicillin).
To identify the definitive pathogen and guide targeted, narrow-spectrum therapy.
3
Select the optimal targeted antimicrobial regimen.
Oral amoxicillin is chosen as the step-down therapy, and atypical coverage (azithromycin) is discontinued.
Antimicrobial stewardship principles require using the narrowest effective agent with the lowest side-effect profile once a pathogen is confirmed.

Key Concept

Patients hospitalized with community-acquired pneumonia who demonstrate clinical stability and have a functioning gastrointestinal tract should be transitioned to a targeted, narrow-spectrum oral antibiotic based on culture susceptibilities.
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Topics

Infectious Diseases

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