Chapter 11: Infective Endocarditis
Causes of Infective Endocarditis
Types of Valve Involvement
- Native Valve Endocarditis (NVE)
- Viridans streptococci (~50–70%)
- Staphylococcus aureus (~25%)
- Enterococci (~10%)
- Gram-positive/negative bacilli
- HACEK group: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella
- Fungi
- Prosthetic Valve Endocarditis (PVE)
- Early: S. epidermidis, S. aureus
- Late: Similar to NVE
Risk Factors
- Cardiac
- Prior infective endocarditis
- Prosthetic valve or cardiac device
- Valvular or congenital heart disease
- Non-Cardiac
- Intravenous drug use
- IV line
- Immunosuppression
- Recent dental/surgical procedures
Diagnosis
- Based on Modified Duke Criteria
- Key indicators:
- Fever (± bacteremia)
- Risk factors
- Blood cultures (3 sets of 10 mL each, aseptically before antimicrobials)
- Echocardiography
- Other microbiological evidence
Additional Evaluation
- Serology for Coxiella, Bartonella, Brucella (if cultures are negative)
- ECG
- Chest X-ray
- Dental evaluation
Rare Pathogen Investigations
- Brucella: Blood cultures, serology, PCR
- Coxiella burnetii: Serology, tissue culture, PCR
- Bartonella: Same as above
- Tropheryma whipplei: Histology + PCR
- Mycoplasma, Legionella: Serology, culture, PCR
- Fungi: Blood cultures + fungal PCR
Empiric Treatment Regimens
NVE – Indolent
- Ampicillin + Gentamicin
- Use Vancomycin if penicillin allergy
NVE – Severe Sepsis (No MDR risk)
- Vancomycin + Gentamicin
- Consider Ciprofloxacin if nephrotoxicity risk
NVE – Severe Sepsis + MDR Risk
- Vancomycin + Meropenem
PVE – Pending/Negative Cultures
- Vancomycin + Gentamicin + Rifampicin
Targeted Treatment by Pathogen
Staphylococcal Endocarditis
- MSSA: Flucloxacillin
- MRSA or allergy: Vancomycin + Rifampicin
- PVE: Add Gentamicin
Streptococcal Endocarditis
- Viridans (MIC ≤ 0.125): Benzylpenicillin or Ceftriaxone ± Gentamicin
- MIC > 0.125: Benzylpenicillin + Gentamicin
- Nutritionally variant: Benzylpenicillin + Gentamicin
- Allergy: Vancomycin or Teicoplanin + Gentamicin
Enterococcal Endocarditis
- Ampicillin or Penicillin + Gentamicin
- Allergy/resistance: Vancomycin or Teicoplanin + Gentamicin
- Ampicillin alone for susceptible strains
Blood Culture-Negative IE
- Brucella: Doxycycline + Cotrimoxazole + Rifampicin
- Bartonella: Ampicillin + Gentamicin or Doxycycline + Gentamicin
- Coxiella burnetii: Doxycycline + Hydroxychloroquine or Ciprofloxacin
HACEK Group Treatment
- Ceftriaxone + Gentamicin
- OR Ampicillin + Gentamicin
Fungal Endocarditis
Candida
- Most common fungal cause
- Initial: Echinocandin or Amphotericin B
- Surgery recommended
- Long-term suppressive therapy needed
Initial Antifungal Options
- Caspofungin, Micafungin, Anidulafungin
- Liposomal Amphotericin B
- Amphotericin B deoxycholate (if lipid unavailable)
Aspergillus
- ~25% of fungal cases
- Requires antifungal + surgical debridement
- Initial: Voriconazole (with drug monitoring)
- Duration: ≥ 6 weeks + long-term prophylaxis