For a patient experiencing symptoms of infective endocarditis, what is the best therapeutic approach if methicillin-susceptible S. aureus is confirmed?

The choice of oxacillin for a patient with methicillin-susceptible Staphylococcus aureus (MSSA) and symptoms of infective endocarditis aligns with established treatment guidelines. MSSA is typically sensitive to penicillinase-resistant penicillins, such as oxacillin and nafcillin. In cases of uncomplicated MSSA endocarditis, the recommended duration of therapy is often 2 weeks when the patient has uncomplicated native valve infection.

Using oxacillin for 2 weeks is appropriate for effectively targeting the organism while minimizing the duration of treatment. This is based on the principle that shorter therapy can be effective for certain patients, especially those who are hemodynamically stable and without complications from the infection.

In contrast, nafcillin, while also an effective choice against MSSA, is typically reserved for endocarditis cases that may require longer treatment durations due to risk factors or in cases involving prosthetic valves. Thus, while effective, the standard recommendation typically suggests 6 weeks of treatment in those particular scenarios.

Vancomycin would be warranted for methicillin-resistant strains of Staphylococcus aureus (MRSA) or in cases where the susceptibility is unknown, making it less appropriate in this specific context of