What is the treatment for infective endocarditis?

Treatment for Infective Endocarditis

The treatment of infective endocarditis requires a multidisciplinary team approach with prompt initiation of appropriate antibiotic therapy based on the causative organism, consideration for surgical intervention in specific cases, and careful monitoring for complications. 1

Antibiotic Therapy Based on Causative Organism

Staphylococcal Endocarditis

• Native Valve Endocarditis (NVE):

  • MSSA (Methicillin-Sensitive S. aureus):
    • Nafcillin or oxacillin 12 g/day IV in 6 equally divided doses for 4-6 weeks 2, 1
    • Plus gentamicin 3 mg/kg/day IV in 2-3 divided doses for the first 2 weeks 2
  • MRSA (Methicillin-Resistant S. aureus):
    • Vancomycin 30 mg/kg/day IV in 2 equally divided doses for 4-6 weeks 2
    • Adjust vancomycin to maintain trough levels of 10-20 μg/mL 2

• Prosthetic Valve Endocarditis (PVE):

  • MSSA:
    • Nafcillin or oxacillin 12 g/day IV in 6 equally divided doses for ≥6 weeks 2, 1
    • Plus rifampin 900 mg/day IV/PO in 3 equally divided doses for ≥6 weeks 2
    • Plus gentamicin 3 mg/kg/day IV/IM in 2-3 divided doses for first 2 weeks 2
  • MRSA:
    • Vancomycin 30 mg/kg/day IV in 2 equally divided doses for ≥6 weeks 2
    • Plus rifampin 900 mg/day IV/PO in 3 equally divided doses for ≥6 weeks 2
    • Plus gentamicin 3 mg/kg/day IV/IM in 2-3 divided doses for first 2 weeks 2

Enterococcal Endocarditis

• Ampicillin 12 g/day IV in 4-6 doses plus gentamicin 3 mg/kg/day IV in 1 dose 1
• For penicillin-allergic patients: vancomycin 30-60 mg/kg/day IV in 2-3 doses plus gentamicin 3 mg/kg/day IV in 1 dose 1

Streptococcal Endocarditis

• Penicillin G or ampicillin for penicillin-susceptible strains 1
• For penicillin-allergic patients: cefazolin or ceftriaxone 1

Duration of Therapy

• Native valve endocarditis: 4-6 weeks 1
• Prosthetic valve endocarditis: minimum of 6 weeks 2, 1

Monitoring During Treatment

• Daily clinical assessment 1
• Serial blood cultures until sterilization is documented 1
• Regular echocardiographic follow-up 1
• Monitoring of renal function 1
• Drug level monitoring for antibiotics like vancomycin and gentamicin 1
  • Trough gentamicin levels <1 mg/L and peak levels 10-12 mg/L 1
  • Trough vancomycin levels 10-15 μg/mL and peak levels 30-45 μg/mL 1

Surgical Indications

Surgery is indicated in approximately 50% of IE cases, including:

• Aortic or mitral valve IE with severe acute regurgitation, obstruction, or fistula causing refractory pulmonary edema or cardiogenic shock 1
• Heart failure with severe regurgitation or obstruction 1
• Uncontrolled infection 1
• Infection caused by fungi or multiresistant organisms 1
• Persistent positive blood cultures despite appropriate antibiotic therapy 1
• Persistent vegetations >10mm after ≥1 embolic episodes 1

Special Considerations

• Early cardiac surgical interventions play an important role in maximizing outcomes in S. aureus PVE, especially in the presence of heart failure 2
• For patients with true penicillin allergies, alternative regimens should be used:
  • For immediate-type hypersensitivity reactions: vancomycin 2
  • For non-immediate-type hypersensitivity reactions: cefazolin may be substituted for nafcillin/oxacillin 2
• Outpatient Parenteral Antimicrobial Therapy (OPAT) can be considered for stable patients with uncomplicated native valve endocarditis after the critical first 2 weeks of treatment 1

Follow-up Care

• Clinical evaluation at 1,3,6, and 12 months 1
• Echocardiography at completion of therapy 1
• Blood cultures if recurrent fever 1
• Dental follow-up and emphasis on prophylaxis for future procedures 1

Pitfalls and Caveats

• Organisms recovered from surgical specimens or blood from patients who have had a bacteriological relapse should be carefully retested for complete antibiotic susceptibility profiles 2
• Adjust antibiotics promptly once pathogen identification and susceptibility results are available, usually within 48 hours 1
• Early consultation with infectious disease specialists is strongly recommended, particularly for non-HACEK Gram-negative endocarditis 1
• Blood cultures should be taken from at least 3 sets from separate venipuncture sites before antibiotic initiation 1