In infective endocarditis (IE) due to viridans streptococcus with MIC ≤ 0.125 mg/L (highly susceptible), the recommended antibiotic regimen for a patient with normal renal function and no penicillin allergy is:
- A Vancomycin IV for 6 weeks
- B Amoxicillin-clavulanate orally for 6 weeks
- C Daptomycin for 4 weeks as it achieves better biofilm penetration
- D Penicillin G or ceftriaxone for 4 weeks; or penicillin G + gentamicin for 2 weeks (short-course for uncomplicated native valve IE) ✓
Explanation
ESC 2023 and AHA 2015 guidelines recommend penicillin G 12–18 million units/day IV for 4 weeks (or ceftriaxone 2 g/day IV/IM for 4 weeks) as standard therapy for highly penicillin-susceptible viridans streptococcal native valve IE. A 2-week short course combining penicillin G with gentamicin (synergistic bactericidal effect) is an option for uncomplicated cases in patients with good renal function and no complications. Vancomycin is reserved for penicillin-allergic patients or resistant organisms. Oral switch strategies are increasingly used after initial parenteral therapy (POET trial).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.