Causes of Infective Endocarditis
By Valve Type:
Risk Factors
- Cardiac: prior IE, prosthetic valve/device, valvular or congenital heart disease
- Non-cardiac: IV drug use, indwelling IV lines, immunosuppression, recent procedures
Diagnosis
- Use modified Duke criteria
- Always obtain 3 sets of blood cultures (before antibiotics)
- Echocardiography (TTE or TEE)
- Other tests: ECG, CXR, serologies (if blood culture negative), valve PCR
Rare Causes: Suggested Lab Tests
Empiric Therapy
NVE (Indolent):
- Ampicillin 2 g IV q4h + Gentamicin 3 mg/kg IV daily
NVE (Severe, no Gram-negative risk):
- Vancomycin 1 g IV q12h + Gentamicin 3 mg/kg IV daily
NVE (Severe, MDR risk):
- Vancomycin 1 g IV q12h + Meropenem 2 g IV q8h
PVE or Blood Culture Negative:
- Vancomycin + Gentamicin + Rifampicin
Staphylococcal Endocarditis
Streptococcal Endocarditis
Treatment depends on MIC:
- MIC ≤ 0.125 mg/L:
- Penicillin 1.2 g IV q4h OR Ceftriaxone 2 g daily
- Add Gentamicin for 2 weeks if synergy needed
- MIC > 0.125–0.5 mg/L:
- Penicillin 2.4 g IV q4h + Gentamicin 3 mg/kg IV daily × 4–6 weeks
Enterococcal Endocarditis
- Ampicillin-susceptible:
- Ampicillin + Gentamicin OR Penicillin + Gentamicin × 4–6 weeks
- Penicillin-resistant or allergy:
- Vancomycin + Gentamicin × 4–6 weeks
- Alternative:
- Teicoplanin + Gentamicin
Blood Culture–Negative Endocarditis (Empiric)
HACEK Endocarditis
Fungal Endocarditis
Candida
- Initial: echinocandin or liposomal amphotericin B
- Surgical valve replacement usually required
- Treat ≥6 weeks post-surgery
- Long-term suppressive antifungal therapy may be needed
Aspergillus
- Voriconazole IV with monitoring
- Surgery essential
- Duration: ≥6 weeks, followed by maintenance therapy
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