What is the treatment for infective endocarditis?

Treatment of Infective Endocarditis

The treatment of infective endocarditis requires targeted antimicrobial therapy based on the causative organism, combined with surgical intervention when indicated, and should be managed by a multidisciplinary team approach. 1

Antimicrobial Therapy Based on Causative Organism

Streptococcal Endocarditis

• Native valve infections:
  • Penicillin-susceptible strains: Penicillin G or amoxicillin for 4 weeks
  • Relatively resistant strains: Penicillin G or amoxicillin plus gentamicin for 2 weeks 2
  • Fully resistant strains: Vancomycin for 4 weeks

Staphylococcal Endocarditis

• Native valve infections:

  • Methicillin-susceptible (MSSA): (Flu)cloxacillin or oxacillin 12 g/day IV in 4-6 doses for 4-6 weeks 2
  • Methicillin-resistant (MRSA): Vancomycin 30 mg/kg/day IV in 2 doses for 4-6 weeks 2, 3

• Prosthetic valve infections:

  • MSSA: (Flu)cloxacillin or oxacillin plus rifampin plus gentamicin for ≥6 weeks 2
  • MRSA: Vancomycin plus rifampin plus gentamicin for ≥6 weeks 2

Enterococcal Endocarditis

• Ampicillin plus gentamicin for 4-6 weeks 2
• For vancomycin-resistant enterococci: Daptomycin plus ampicillin or linezolid for ≥8 weeks 2

HACEK Organisms

• Ceftriaxone 2 g/day for 4 weeks in native valve and 6 weeks in prosthetic valve endocarditis 2

Fungal Endocarditis

• Combined antifungal therapy plus surgical valve replacement 2
• Mortality is very high (>50%) 2

Blood Culture-Negative Endocarditis

• Empiric therapy for native valve: Ampicillin-sulbactam plus gentamicin for 4-6 weeks 2
• For specific suspected pathogens:
  • Brucella: Doxycycline plus cotrimoxazole plus rifampin for ≥3-6 months 1
  • Q fever (C. burnetii): Doxycycline plus hydroxychloroquine for >18 months 1
  • Bartonella: Doxycycline plus gentamicin (doxycycline for 4 weeks, gentamicin for 2 weeks) 1

Empirical Therapy

When immediate treatment is necessary before culture results:

Native Valve Endocarditis

• Community-acquired: Vancomycin plus ceftriaxone 1
• Healthcare-associated: Vancomycin plus gentamicin 1

Prosthetic Valve Endocarditis

• Early (<1 year post-surgery): Vancomycin plus gentamicin plus rifampin 2, 1
• Late (>1 year post-surgery): Same as native valve endocarditis plus rifampin 2

Monitoring During Treatment

• Daily clinical assessment
• Serial blood cultures until sterilization is documented
• Regular echocardiographic follow-up
• Monitor renal function
• Drug level monitoring:
  • Gentamicin: Target trough <1 mg/L, peak 10-12 mg/L 2
  • Vancomycin: Target trough 10-15 μg/mL, peak 30-45 μg/mL 2, 3

Surgical Indications

Surgery should be considered in the following situations:

• Heart failure due to valvular dysfunction
• Uncontrolled infection despite appropriate antibiotics
• Large mobile vegetations (>10mm) with embolic risk
• Perivalvular abscess or fistula formation
• Prosthetic valve infection, especially with S. aureus or fungi 1

Special Considerations

• Multivalvular endocarditis has worse outcomes compared to single-valve involvement, with increased risk of mortality, heart failure, and need for surgery 4
• Healthcare-associated IE and drug-use-associated IE are increasing in prevalence, with Staphylococcus aureus as the leading cause 5, 6
• Multidrug-resistant organisms pose additional challenges, requiring specialized antimicrobial regimens 5

Follow-up Care

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

Common Pitfalls and Caveats

• Inadequate duration of therapy is a common cause of treatment failure
• Failure to identify and drain metastatic sites of infection
• Delayed surgical intervention when indicated
• Inadequate monitoring of antibiotic levels, particularly for vancomycin and aminoglycosides
• Failure to recognize and manage complications such as heart failure, embolic events, or perivalvular extension

The management of infective endocarditis has evolved significantly, with recent data showing an increasing incidence despite improvements in diagnostics and treatment 6. A multidisciplinary team approach with prompt initiation of appropriate antimicrobial therapy and consideration for surgical intervention in specific cases is essential for optimal outcomes.