What is the diagnosis and treatment of endocarditis (infection of the inner lining of the heart)?

From the Guidelines

Endocarditis treatment should prioritize immediate hospitalization and 4-6 weeks of intravenous antibiotics, with the selection of empirical therapy based on epidemiological features, history of prior infections, and clinical course, as recommended by the American Heart Association 1.

Key Considerations

• Blood cultures before antibiotic initiation are crucial for identifying the causative organism and determining appropriate treatment.
• For patients with acute clinical presentations of native valve infection, coverage for S aureus, β-hemolytic streptococci, and aerobic Gram-negative bacilli is reasonable 1.
• For patients with a subacute presentation of native valve endocarditis, coverage of S aureus, viridans group streptococci, enterococci, and HACEK group organisms is recommended 1.
• Patients with culture-negative prosthetic valve infection should receive vancomycin if onset of symptoms begins within 1 year of prosthetic valve placement to provide coverage of oxacillin-resistant staphylococci 1.

Treatment Options

• For streptococcal endocarditis, penicillin G (12-18 million units daily) plus gentamicin (3mg/kg/day) is standard therapy.
• For staphylococcal infections, nafcillin or oxacillin (2g IV every 4 hours) is preferred, with vancomycin (15-20mg/kg every 12 hours) used for methicillin-resistant strains.
• Surgery may be necessary for severe valve damage, persistent infection, heart failure, or large vegetations.

Prevention

• Prophylactic antibiotics (amoxicillin 2g orally 30-60 minutes before procedures) are recommended for high-risk patients undergoing dental procedures.
• Risk factors for endocarditis include previous valve damage, artificial heart valves, intravenous drug use, and certain congenital heart defects.

From the FDA Drug Label

The efficacy of daptomycin for injection in the treatment of adult patients with S. aureus bacteremia was demonstrated in a randomized, controlled, multinational, multicenter, open-label trial. In the ITT population, there were 182 patients with bacteremia and 53 patients with infective endocarditis as assessed by the Adjudication Committee, including 35 with right-sided endocarditis and 18 with left-sided endocarditis The overall Adjudication Committee success rates in the ITT population were 44. 2% (53/120) in patients treated with daptomycin for injection and 41.7% (48/115) in patients treated with comparator (difference = 2.4% [95% CI −10.2,15.1]). Adjudication Committee success rates are shown in Table 17.

Daptomycin for Endocarditis: Daptomycin is effective in treating S. aureus bacteremia and endocarditis.

• The success rate for daptomycin in treating endocarditis is 44.2% in the ITT population.
• The success rate for the comparator is 41.7% in the ITT population.
• The difference in success rates between daptomycin and the comparator is 2.4%. 2

From the Research

Definition and Treatment of Endocarditis

• Endocarditis is a difficult-to-treat infectious disease, with a mortality rate ranging from 20 to 25% despite recent medical advances 3.
• The treatment approach to endocarditis is similar for both adult and pediatric patients, with the goal of achieving sterilization of the cardiac vegetations 4.
• The choice of antibacterial treatment depends on the susceptibility profile of the causative organism, with vancomycin or gentamicin recommended for enterococcal endocarditis, and oxacillin or nafcillin with or without gentamicin for staphylococcal endocarditis 4.

Antibacterial Treatment Regimens

• For staphylococcal endocarditis, anti-staphylococcal penicillins, such as cefazolin, are recommended for methicillin-susceptible isolates, while vancomycin is recommended for methicillin-resistant isolates 5.
• The addition of gentamicin during the first 2 weeks and rifampin throughout the whole treatment duration is recommended for staphylococcal prosthetic-valve endocarditis 5.
• The optimal duration of antibacterial treatment is 4 weeks for most native valve endocarditis and 6 weeks for prosthetic-valve endocarditis 5.

Prophylaxis and Prevention

• Prophylactic antibacterial therapy is recommended for procedures that may cause bacteraemia, such as dental extractions and oral, respiratory tract, genitourinary, gastrointestinal, or oesophageal procedures 4.
• The American Heart Association recommends ampicillin + gentamicin or vancomycin + gentamicin for prophylaxis in high-risk patients undergoing genitourinary and gastrointestinal surgical procedures 4.
• However, the efficacy of antibiotic prophylaxis is not rigorously proven, and current guidelines recommend it only for patients with a high risk for an adverse outcome 3.

Emerging Resistance and Combination Therapies

• The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and drug-resistant strains of Streptococcus pneumoniae is a concern in the treatment of endocarditis 4.
• Combination therapies, such as daptomycin-oxacillin, may be effective against MRSA strains with evolving oxacillin susceptibility, also known as the "seesaw effect" 6.
• The use of newer agents, such as quinupristin/dalfopristin, may also be considered for the treatment of resistant bacterial endocarditis 4.