What is the treatment for infective endocarditis?

Treatment for Infective Endocarditis

The treatment of infective endocarditis requires targeted antimicrobial therapy based on the causative organism, with empirical therapy initiated promptly after blood cultures are obtained, typically consisting of bactericidal antibiotics administered intravenously for 4-6 weeks. 1, 2

Initial Approach

• Three sets of blood cultures should be drawn at 30-minute intervals before initiating antibiotics to identify the causative pathogen 1, 2
• Treatment should be started promptly after obtaining blood cultures, especially in acutely ill patients 1, 2
• The choice of empirical therapy depends on several factors:
  • Previous antibiotic exposure
  • Whether infection affects native or prosthetic valve
  • Setting of infection (community-acquired, nosocomial, healthcare-associated)
  • Local epidemiology and resistance patterns 1, 2

Empirical Antibiotic Regimens

For Community-Acquired Native Valve Endocarditis:

• First-line regimen: Ampicillin (12 g/day IV in 4-6 doses) plus (flu)cloxacillin/oxacillin plus gentamicin (3 mg/kg/day IV or IM in 1 dose) 2
• For penicillin-allergic patients: Vancomycin (30-60 mg/kg/day IV in 2-3 doses) plus gentamicin (3 mg/kg/day IV or IM in 1 dose) 1, 2

For Early Prosthetic Valve Endocarditis (<12 months post-surgery) or Healthcare-Associated Endocarditis:

• Vancomycin (30 mg/kg/day IV in 2 doses) plus gentamicin (3 mg/kg/day IV or IM in 1 dose) plus rifampin (900-1200 mg IV or orally in 2-3 divided doses) 1, 2
• Rifampin should be started 3-5 days after vancomycin and gentamicin 1

Pathogen-Specific Treatment

Staphylococcal Endocarditis:

• For methicillin-susceptible S. aureus: Anti-staphylococcal penicillins (oxacillin/nafcillin) or cefazolin for 4-6 weeks 3
• For methicillin-resistant S. aureus: Vancomycin or daptomycin for 4-6 weeks 4, 3
• For prosthetic valve endocarditis: Add gentamicin for first 2 weeks and rifampin throughout the 6-week treatment 3

Streptococcal Endocarditis:

• For penicillin-sensitive viridans streptococci: Penicillin G alone for 4 weeks or combined with an aminoglycoside for 2 weeks 5, 6
• For relatively resistant streptococci: Longer courses (4-6 weeks) with combination therapy 5

Enterococcal Endocarditis:

• Penicillin G or ampicillin plus gentamicin for 4-6 weeks 6
• Alternative approaches include short-course aminoglycoside therapy or double-beta-lactam combinations 7

HACEK Organisms:

• Ceftriaxone (2 g/day IV) for 4 weeks in native valve IE and 6 weeks in prosthetic valve IE 1, 2
• Alternative: Ampicillin (12 g/day IV in 4-6 doses) plus gentamicin for 4-6 weeks 1

Non-HACEK Gram-Negative Bacteria:

• Early surgery plus long-term therapy (at least 6 weeks) with beta-lactams and aminoglycosides 1
• Consider adding quinolones or cotrimoxazole based on susceptibility 1, 2

Fungal Endocarditis:

• Combined antifungal therapy plus surgical valve replacement 1, 2
• Mortality remains high (>50%) despite aggressive treatment 1

Blood Culture-Negative Endocarditis:

• Consultation with an infectious disease specialist is strongly recommended 1, 2
• Treatment options based on suspected pathogens (see Table 19 in guidelines) 1
• Common empirical regimens include doxycycline plus hydroxychloroquine for suspected Q fever or Bartonella 1

Duration of Therapy

• Native valve endocarditis: Generally 4 weeks 3
• Prosthetic valve endocarditis: Generally 6 weeks 3
• Specific pathogens may require longer therapy (e.g., Q fever requires ≥18 months) 1

Outpatient Parenteral Antibiotic Therapy (OPAT)

• OPAT can be considered after the critical phase (first 2 weeks) of treatment 1
• Suitable for medically stable patients without complications 1
• Not recommended for patients with heart failure, concerning echocardiographic features, neurological signs, or renal impairment 1
• Requires regular follow-up (nurses daily, physician 1-2 times/week) 1

Surgical Considerations

• Approximately 50% of IE patients require surgery due to severe complications 1
• Main indications include progressive heart failure, uncontrolled infection, and prevention of systemic embolism 1

Monitoring Treatment Success

• Clinical improvement with resolution of fever and other symptoms 8
• Negative blood cultures 8
• Prevention of complications such as embolism or relapse 8
• For specific pathogens, success may be defined by serological markers (e.g., antibody titers for Brucella or C. burnetii) 8

Common Pitfalls to Avoid

• Delayed initiation of appropriate antibiotics can worsen outcomes 8
• Inadequate duration of therapy may lead to treatment failure 8
• Failure to monitor for drug toxicity, especially with aminoglycosides 1, 2
• Not considering surgery when indicated 1
• Overlooking the possibility of blood culture-negative pathogens 1