From the Guidelines
Management of methicillin-sensitive Staphylococcus aureus (MSSA) bioprosthetic aortic valve endocarditis requires prompt antibiotic therapy with nafcillin or oxacillin, plus rifampin, and gentamicin for the initial 2 weeks, as recommended by the American Heart Association 1. The recommended antibiotic regimen consists of intravenous nafcillin or oxacillin 12 g/24 h in 6 equally divided doses for ≥6 weeks, plus rifampin 900 mg per 24 h IV or orally in 3 equally divided doses for ≥6 weeks, and gentamicin 3 mg/kg per 24 h IV or IM in 2 or 3 equally divided doses for 2 weeks 1. Key considerations in management include:
- Early surgical evaluation, with indications for valve replacement including heart failure, persistent bacteremia despite appropriate antibiotics, large vegetations (>10mm), embolic events, or perivalvular abscess formation 1
- Transesophageal echocardiography to assess vegetation size, valve function, and potential complications
- Blood cultures obtained every 24-48 hours until sterile, and antibiotic therapy adjusted based on minimum inhibitory concentration testing
- Surgical principles in re-operation for prosthetic valve endocarditis involve removal of the infected prosthesis, extensive debridement, and laboratory examination of debrided tissue to identify organisms 1 MSSA endocarditis carries a better prognosis than methicillin-resistant strains due to the superior bactericidal activity of beta-lactam antibiotics, but still requires aggressive management to prevent complications such as embolization, heart failure, and death.
From the FDA Drug Label
Duration of therapy varies with the type of severity of infection as well as the overall condition of the patient, therefore it should be determined by the clinical and bacteriological response of the patient In severe staphylococcal infections, therapy with oxacillin should be continued for at least 14 days. Therapy should be continued for at least 48 hours after the patient has become afebrile, asymptomatic, and cultures are negative. Treatment of endocarditis and osteomyelitis may require a longer duration of therapy
The management of MSSA bioprosthetic aortic valve endocarditis with oxacillin may require at least 14 days of therapy for severe staphylococcal infections, and longer duration for endocarditis. The therapy should be continued for at least 48 hours after the patient has become afebrile, asymptomatic, and cultures are negative 2.
- Key considerations:
- Duration of therapy varies with the type and severity of infection
- Clinical and bacteriological response of the patient should guide therapy
- Severe staphylococcal infections require at least 14 days of therapy
- Endocarditis may require longer duration of therapy
From the Research
Management of MSSA Bioprosthetic AV Endocarditis
- The management of MSSA bioprosthetic AV endocarditis typically involves antibiotic therapy, with vancomycin being the cornerstone of treatment for MRSA infections, including endocarditis 3.
- However, in cases where vancomycin therapy is ineffective, alternative antibiotics such as daptomycin may be used 3.
- Surgical valve replacement is often recommended for the treatment of prosthetic valve endocarditis (PVE), but in some cases, medical therapy may be sufficient, especially if surgery is not an option 3, 4.
- The choice between bioprosthetic and mechanical valves for aortic valve replacement should take into account the individual patient's risk factors, including the risk of infective endocarditis, with bioprosthetic valves potentially being associated with a higher risk of infective endocarditis 5.
- In patients aged 60 years and younger, mechanical valves may be associated with lower all-cause mortality compared to bioprosthetic valves 6.
Treatment Options
- Antibiotic therapy: vancomycin, daptomycin, quinupristin, dalfopristin, linezolid 3
- Surgical valve replacement: recommended for PVE, but may not always be necessary or possible 3, 7, 4
- Medical therapy: may be sufficient in some cases, especially if surgery is not an option 3, 4