What is the treatment for infective endocarditis?

Treatment of Infective Endocarditis

The treatment of infective endocarditis requires a combination of appropriate antibiotics for 4-6 weeks, with specific regimens based on the causative organism, and surgical intervention in approximately 50% of cases, particularly those with heart failure, uncontrolled infection, or large vegetations. 1

Antibiotic Therapy Based on Causative Organism

Viridans Streptococci or S. bovis

• First-line treatment: Aqueous crystalline penicillin G (18-30 million U/24h IV in 6 equally divided doses) OR ampicillin (12g/24h IV in 6 equally divided doses) for 4 weeks 1
• Duration: 4 weeks for native valve endocarditis with symptoms <3 months; 6 weeks for symptoms >3 months 1
• For penicillin allergy: Vancomycin 30 mg/kg/24h IV in 2 equally divided doses for 4 weeks 1

Enterococci

• First-line treatment: Ampicillin (12g/24h IV in 6 equally divided doses) OR penicillin G (18-30 million U/24h IV) PLUS gentamicin (3 mg/kg/24h IV/IM in 3 equally divided doses) for 4-6 weeks 1
• For penicillin-resistant enterococci: Vancomycin (30 mg/kg/24h IV in 2 equally divided doses) plus gentamicin (3 mg/kg/24h IV/IM in 3 equally divided doses) for 6 weeks 1

Staphylococcus aureus

• Native valve: Nafcillin or oxacillin (12g/24h IV in 6 equally divided doses) for 6 weeks for MSSA 2
• For MRSA: Vancomycin (30 mg/kg/24h IV in 2 equally divided doses) for 6 weeks 2
• Right-sided endocarditis: Daptomycin is FDA-approved for S. aureus bloodstream infections, including right-sided infective endocarditis 3
  • Note: Daptomycin is NOT indicated for left-sided infective endocarditis due to S. aureus 3

Prosthetic Valve Endocarditis

• Early (<1 year post-surgery):
  • Vancomycin (30 mg/kg/24h IV in 2 equally divided doses) PLUS
  • Gentamicin (3 mg/kg/24h IV/IM in 3 equally divided doses) for 2 weeks PLUS
  • Cefepime (6g/24h IV in 3 equally divided doses) PLUS
  • Rifampin (900 mg/24h PO/IV in 3 equally divided doses) for 6 weeks 2
• Late (>1 year post-surgery): Same regimens as for native valve endocarditis with the addition of rifampin 2

Culture-Negative Endocarditis

• Suspected Bartonella: Ceftriaxone (2g/24h IV/IM) for 6 weeks PLUS gentamicin (3 mg/kg/24h IV/IM in 3 equally divided doses) for 2 weeks PLUS doxycycline (200 mg/24h IV or PO in 2 equally divided doses) for 6 weeks 2
• Documented Bartonella: Doxycycline (200 mg/24h IV or PO in 2 equally divided doses) for 6 weeks PLUS gentamicin (3 mg/kg/24h IV/IM in 3 equally divided doses) for 2 weeks 2

Fungal Endocarditis

• Mandatory valve replacement plus parenteral antifungal agent (usually amphotericin B-containing product) for 6 weeks, followed by lifelong oral azole suppressive therapy 2

Indications for Surgical Intervention

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

1. Aortic/mitral valve IE with severe acute regurgitation, obstruction, or fistula causing refractory pulmonary edema or cardiogenic shock 1
2. Heart failure with severe regurgitation or obstruction 1
3. Uncontrolled infection (persistent positive blood cultures despite appropriate antibiotic therapy) 1
4. Infection caused by fungi or multiresistant organisms 1
5. Persistent vegetations >10mm after ≥1 embolic episodes 1
6. Prosthetic valve infection, regardless of fungal causes 2
7. S. aureus prosthetic valve endocarditis (early surgical intervention maximizes outcomes) 1

Monitoring During Treatment

• Daily clinical assessment 1
• Serial blood cultures until sterilization is documented 1
• Regular echocardiographic follow-up 1
• Monitor 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
  • Trough vancomycin levels 10-15 μg/mL and peak levels 30-45 μg/mL

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

Important Considerations

• Early consultation with infectious disease specialists is strongly recommended, particularly for non-HACEK Gram-negative endocarditis 1
• For injection drug users (IDUs), who have a higher incidence of IE (1.5 to 3.3 cases per 1000 person-years), treatment approach remains the same but recurrence risk is higher 2
• HIV-infected IDUs with severe immunosuppression may have higher mortality 2
• Combination antibiotic therapy is particularly important for enterococcal endocarditis 4