What is the treatment for endocarditis?

Treatment of Endocarditis

The treatment of infective endocarditis requires prolonged intravenous bactericidal antibiotics specific to the causative organism, often in combination with surgical intervention for complicated cases. 1 The choice of antibiotic therapy depends on the infecting organism, valve type (native vs. prosthetic), and patient characteristics.

Antibiotic Treatment by Pathogen

Staphylococcal Endocarditis

Native Valve Infections

• Methicillin-susceptible S. aureus (MSSA):

  • First-line: (Flu)cloxacillin or oxacillin 12 g/day IV in 4-6 doses for 4-6 weeks 1
  • Pediatric dose: 200-300 mg/kg/day IV in 4-6 equally divided doses 1
  • Note: Addition of gentamicin is no longer recommended due to lack of proven benefit and increased renal toxicity 1

• Methicillin-resistant S. aureus (MRSA) or penicillin-allergic patients:

  • Vancomycin 30-60 mg/kg/day IV in 2-3 doses for 4-6 weeks 1, 2
  • Alternative: Daptomycin 10 mg/kg/day IV once daily for 4-6 weeks 1
  • For non-anaphylactic penicillin allergy: Cefazolin 6 g/day or cefotaxime 6 g/day IV in 3 doses 1

Prosthetic Valve Infections

• Methicillin-susceptible staphylococci:

  • (Flu)cloxacillin or oxacillin 12 g/day IV in 4-6 doses for ≥6 weeks, PLUS
  • Rifampin 900-1200 mg IV or orally in 2-3 divided doses for ≥6 weeks, PLUS
  • Gentamicin 3 mg/kg/day IV or IM in 1-2 doses for first 2 weeks 1
  • Note: Start rifampin 3-5 days after initiating other antibiotics 1

• Methicillin-resistant staphylococci or penicillin-allergic patients:

  • Vancomycin 30-60 mg/kg/day IV in 2-3 doses for ≥6 weeks, PLUS
  • Rifampin and gentamicin as above 1, 2

Enterococcal Endocarditis

• Penicillin-susceptible strains (MIC ≤8 mg/L):

  • Ampicillin (preferred) or amoxicillin 12 g/day IV in 4-6 doses, PLUS
  • Gentamicin 3 mg/kg/day IV or IM in 1 dose for 4-6 weeks 1
  • For high-level aminoglycoside resistance (HLAR): Consider streptomycin if still active 1

• Vancomycin-resistant enterococci:

  • Consult infectious disease specialist - these cases require specialized management 1

Blood Culture-Negative Endocarditis

Treatment depends on the suspected pathogen:

• Brucella spp.: Doxycycline (200 mg/24h) + cotrimoxazole (960 mg/12h) + rifampin (300-600 mg/24h) orally for ≥3-6 months 1

• Coxiella burnetii (Q fever): Doxycycline (200 mg/24h) + hydroxychloroquine (200-600 mg/24h) orally for >18 months 1

• Bartonella spp.: Doxycycline (100 mg/12h) orally for 4 weeks + gentamicin (3 mg/24h) IV for 2 weeks 1

Empirical Therapy

When the causative organism is unknown, empirical therapy should be initiated after obtaining blood cultures:

Community-acquired native valve or late prosthetic valve endocarditis:

• Ampicillin 12 g/day IV in 4-6 doses, PLUS
• (Flu)cloxacillin or oxacillin 12 g/day IV in 4-6 doses, PLUS
• Gentamicin 3 mg/kg/day IV or IM in 1 dose 1

Early prosthetic valve (<12 months post-surgery) or healthcare-associated endocarditis:

• Vancomycin 30 mg/kg/day IV in 2 doses, PLUS
• Gentamicin 3 mg/kg/day IV or IM in 1 dose, PLUS
• Rifampin 900-1200 mg IV or orally in 2-3 divided doses (for PVE) 1

Surgical Management

Surgical intervention should be considered in the following situations:

• Heart failure due to valve dysfunction
• Uncontrolled infection (abscess, persistent bacteremia)
• Prevention of embolic events (large vegetations)
• Prosthetic valve endocarditis, especially with S. aureus infection 1, 3

Duration of Therapy

• Native valve endocarditis: 4-6 weeks of IV antibiotics 1, 4
• Prosthetic valve endocarditis: At least 6 weeks of IV antibiotics 1
• Fungal endocarditis: Combined antifungal therapy and surgical valve replacement 1

Important Considerations

• Monitoring therapy: Regular clinical assessment, blood cultures, and serum antibiotic levels (for vancomycin, aminoglycosides) 1, 5

• Antibiotic administration: Cell-wall active antibiotics (beta-lactams, glycopeptides) require time-dependent dosing, while aminoglycosides require concentration-dependent dosing 5

• Consultation: Complex cases should be managed by an Endocarditis Team or with infectious disease specialist consultation, especially for blood culture-negative endocarditis 1

• Pitfalls to avoid:

  • Delaying treatment in suspected cases (obtain cultures then start empiric therapy)
  • Inadequate duration of therapy (risk of relapse)
  • Failure to identify complications requiring surgical intervention
  • Inappropriate antibiotic selection for resistant organisms 1, 4