Treatment of Methicillin-Sensitive Staphylococcus aureus (MSSA) Bacteremia

First-Line Treatment Options

The American Heart Association recommends antistaphylococcal beta-lactams such as nafcillin, oxacillin, or cefazolin as first-line treatments for MSSA bacteremia due to their superior efficacy compared to vancomycin 1
Nafcillin or oxacillin 2g IV every 6 hours is a preferred agent for MSSA bacteremia 2, 3
Cefazolin 1-2g IV every 8 hours is a recommended treatment option for MSSA bacteremia 2

For patients with confirmed severe beta-lactam allergy, vancomycin 15-20 mg/kg IV every 8-12 hours can be used as an alternative treatment option 4, 6
Nafcillin is preferred over cefazolin for brain abscess complicating MSSA infective endocarditis due to better blood-brain barrier penetration 1

The Infectious Diseases Society of America recommends obtaining follow-up blood cultures 2-4 days after initial positive cultures to document clearance of bacteremia 4, 6
Echocardiography is recommended for all adult patients with S. aureus bacteremia to rule out endocarditis 4, 8

The American College of Cardiology states that beta-lactams (nafcillin, oxacillin, cefazolin) are superior to vancomycin for MSSA bacteremia, with significantly lower treatment failure rates 1
The addition of gentamicin to treatment regimens is not recommended for native valve endocarditis or bacteremia due to increased nephrotoxicity without improved outcomes 1, 4
The Infectious Diseases Society of America recommends against the addition of rifampin for uncomplicated bacteremia or native valve endocarditis 4, 6