A 54-year-old man is evaluated in the hospital on his third day of admission for community… — USMLE Step 2 CK

A $54$ -year-old man is evaluated in the hospital on his third day of admission for community-acquired pneumonia. He was initially started on empiric therapy with intravenous ceftriaxone and oral azithromycin. His cough and shortness of breath have significantly improved, and he has been afebrile for the past $24$ hours. He is currently tolerating a regular diet. Sputum cultures collected on admission grew *Streptococcus pneumoniae*. Susceptibility testing reveals that the isolate is susceptible to penicillin, amoxicillin, ceftriaxone, levofloxacin, and vancomycin, and resistant to azithromycin. He has no known drug allergies. Vital signs are temperature $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), pulse $76/\text{min}$ , respirations $14/\text{min}$ , and blood pressure $124/78\text{ mmHg}$ . Pulse oximetry is $97\%$ on room air. The patient is being prepared for discharge. Which of the following is the most appropriate antimicrobial regimen to prescribe for this patient upon discharge?

Oral amoxicillinAnswer
B
Oral amoxicillin-clavulanate
C
Oral levofloxacin
D
Oral linezolid
E
Intravenous ceftriaxone

Answer

Oral amoxicillin is the most appropriate discharge antibiotic regimen.

The most appropriate next step is to transition this patient to oral amoxicillin. He is clinically stable, afebrile, and tolerating oral intake, which meets all criteria for transitioning from intravenous to oral antibiotics. The sputum culture grew *Streptococcus pneumoniae* that is susceptible to penicillin and amoxicillin. Principles of antimicrobial stewardship dictate that once a pathogen is identified and susceptibilities are known, empiric broad-spectrum therapy should be de-escalated to the narrowest effective agent. Oral amoxicillin provides excellent targeted coverage for susceptible *S. pneumoniae* and is the preferred first-line step-down agent in this clinical scenario.

Step-by-Step Solution

Assess the patient's clinical stability for transition to oral therapy.

The patient is afebrile, clinically improving, and tolerating an oral diet, making him eligible for oral step-down therapy.

Transitioning to oral antibiotics reduces hospital stay and intravenous catheter complications.

Evaluate the sputum culture and susceptibility results.

The infection is driven by Streptococcus pneumoniae that is susceptible to penicillin and amoxicillin.

Culture data guides the de-escalation of empiric therapy.

Select the narrowest-spectrum effective oral antibiotic.

Oral amoxicillin is selected over broader agents.

This adheres to antimicrobial stewardship principles, preventing resistance and minimizing adverse effects.

Key Concept

Antibiotic de-escalation involves transitioning from broad-spectrum empiric therapy to the narrowest-spectrum effective oral agent once culture and susceptibility data are available and the patient is clinically stable.

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