Question

During morning rounds, the internal medicine team evaluates a male patient in his late fifties who was admitted three days prior for community-acquired pneumonia. On presentation to the emergency department, his temperature was $39.2^\circ\text{C}$ ($102.6^\circ\text{F}$) and chest imaging revealed a right lower lobe consolidation. Initial empiric therapy with intravenous ceftriaxone and oral azithromycin was instituted.

Currently, the patient reports significant symptomatic improvement, noting decreased cough and resolution of shortness of breath. He is comfortably eating a regular diet. His vital signs show a temperature of $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure of $124/82\text{ mm Hg}$, heart rate of $78/\text{min}$, and respiratory rate of $16/\text{min}$.

A high-quality sputum specimen collected prior to antibiotic administration has grown heavy *Streptococcus pneumoniae*. Antimicrobial susceptibility testing indicates that the organism is sensitive to penicillin, amoxicillin, ceftriaxone, and levofloxacin, but demonstrates resistance to macrolides.

Which of the following is the most appropriate next step in the pharmacologic management of this patient?