What is the treatment for left-sided endocarditis?

Treatment of Left-Sided Endocarditis

The treatment of left-sided endocarditis requires a combination of appropriate antimicrobial therapy for 4-6 weeks along with consideration for early surgical intervention in cases with complications such as heart failure, uncontrolled infection, or high risk of embolism. 1

Antimicrobial Therapy

For Native Valve Endocarditis (NVE)

• Methicillin-Susceptible Staphylococcus aureus (MSSA):

  • Nafcillin or oxacillin for 6 weeks is recommended for uncomplicated left-sided NVE 1
  • For complicated infections (perivalvular abscess, septic metastatic complications), at least 6 weeks of therapy is required 1
  • Gentamicin should NOT be used for treatment of NVE caused by MSSA 1

• Methicillin-Resistant Staphylococcus aureus (MRSA):

  • Vancomycin is the recommended treatment 1
  • Daptomycin (≥8-9 mg/kg per dose) may be a reasonable alternative to vancomycin 1
  • Selection of daptomycin dosing should be assisted by infectious diseases consultation 1

• Streptococcal Endocarditis:

  • For penicillin-sensitive viridans or nonenterococcal group D streptococci: aqueous penicillin G for 4 weeks or combined penicillin and streptomycin for 2 weeks 2

• Enterococcal Endocarditis:

  • Treatment for 4-6 weeks with aqueous penicillin G together with either streptomycin or gentamicin 2

For Prosthetic Valve Endocarditis (PVE)

• Early PVE or healthcare-associated IE regimens should cover methicillin-resistant staphylococci, enterococci, and non-HACEK Gram-negative pathogens 1
• Longer duration of therapy is typically required compared to NVE

Surgical Management

Surgery should be considered in the following scenarios:

Heart Failure Indications (Class I)

• Aortic or mitral NVE/PVE with severe acute regurgitation, obstruction, or fistula causing refractory pulmonary edema or cardiogenic shock (Emergency surgery) 1
• Aortic or mitral NVE/PVE with severe regurgitation or obstruction causing symptoms of heart failure or echocardiographic signs of poor hemodynamic tolerance (Urgent surgery) 1

Uncontrolled Infection Indications (Class I)

• Locally uncontrolled infection (abscess, false aneurysm, fistula, enlarging vegetation) (Urgent surgery) 1
• Infection caused by fungi or multiresistant organisms (Urgent/elective surgery) 1
• Persisting positive blood cultures despite appropriate antibiotic therapy (Urgent surgery) 1

Prevention of Embolism Indications (Class I)

• Persistent vegetations >10 mm after one or more embolic episodes despite appropriate antibiotic therapy (Urgent surgery) 1
• Large vegetations (>10 mm) with severe valve stenosis or regurgitation and low operative risk (Urgent surgery) 1

Outpatient Parenteral Antibiotic Therapy (OPAT)

OPAT can be considered in two phases:

• Critical phase (weeks 0-2):

  • Inpatient treatment is preferred during this phase 1
  • OPAT may be considered only for stable patients with uncomplicated infections caused by oral streptococci or Streptococcus bovis 1

• Continuation phase (beyond week 2):

  • OPAT can be considered if the patient is medically stable 1
  • OPAT should NOT be used if the patient has heart failure, concerning echocardiographic features, neurological signs, or renal impairment 1

Recent Advances

• Partial oral antibiotic therapy may be considered for stable patients with left-sided endocarditis after at least 10 days of intravenous antibiotics, based on the POET trial 3
• This approach was found to be non-inferior to continued intravenous treatment in selected stable patients 3

Common Pitfalls and Caveats

• Avoid gentamicin for MSSA/MRSA native valve endocarditis due to increased risk of nephrotoxicity without improved outcomes 1
• In cases of brain abscess resulting from MSSA IE, nafcillin should be used instead of cefazolin due to better blood-brain barrier penetration 1, 4
• For patients with a well-defined history of non-anaphylactoid reactions to penicillins, a first-generation cephalosporin such as cefazolin may be reasonable 1
• Up to 50% of patients with IE will require cardiothoracic surgical intervention, so early consultation with a cardiac surgeon is essential 5, 1
• Vancomycin is often considered inferior to β-lactams for MSSA infections, so β-lactam allergy evaluation should be conducted whenever vancomycin is considered 1

Monitoring

• Regular clinical assessment for signs of heart failure, embolic events, or neurological complications 1
• Repeat blood cultures to confirm clearance of bacteremia 5
• Echocardiographic follow-up to monitor vegetation size and valvular function 1