Clinical Pearls & Morning Reports
Published August 5, 2020
Rheumatic heart disease, the most common predisposing condition for infective endocarditis in developing countries, is uncommon in developed countries, where the most frequent predisposing cardiac conditions are degenerative valvular diseases, congenital valvular abnormalities, and intracardiac devices. Read the NEJM Clinical Practice Article here.
Q: What are the noncardiac risk factors for native-valve infective endocarditis?
A: Noncardiac risk factors include poor dentition, intravenous drug use, hemodialysis, chronic liver disease, diabetes, compromised immunity, neoplastic disease, and indwelling intravascular devices.
Q: What organisms are most commonly implicated in cases of native-valve infective endocarditis?
A: Worldwide, gram-positive bacteria account for approximately 80% of cases of native-valve infective endocarditis. These bacteria include Staphylococcus aureus in 35 to 40% of cases of native-valve infective endocarditis, streptococci in 30 to 40% (viridans streptococci in approximately 20% and Streptococcus gallolyticus [formerly S. bovis] and other streptococci in approximately 15%), and enterococci in 10%.
A: Fever and heart murmur, the two signature features of infective endocarditis, are present in approximately 90% and 75% of patients, respectively. Infective endocarditis may present acutely with a rapidly progressive course complicated by congestive heart failure, stroke, systemic or pulmonary embolization, severe sepsis or septic shock, or subacutely with nonspecific symptoms such as low-grade fever, malaise, chills, sweats, dyspnea, back pain, arthralgias, and weight loss over a period of weeks or sometimes months. Microembolic or immunologic phenomena such as splinter hemorrhage, conjunctival hemorrhage, Osler nodes (distal vasculitic lesions of the fingers and toes), Janeway lesions (vasculitic lesions of the palms and soles), and Roth spots (hemorrhagic retinal lesions) are present in 5 to 10% of patients.
A: For susceptible strains, beta-lactam antibiotics are the cornerstone of definitive therapy. These agents are preferred over others unless the patient cannot take them without adverse effects or there is a documented immediate (type I) hypersensitivity reaction. Infective endocarditis that is caused by penicillin-nonsusceptible strains of viridans group streptococci, S. gallolyticus, abiotrophia species, or granulicatella species can be treated with a combination of penicillin or ceftriaxone plus gentamicin; vancomycin monotherapy is an option, although there is less overall experience with this agent. An antistaphylococcal penicillin (e.g., oxacillin) is the drug of choice for infective endocarditis that is caused by methicillin-susceptible strains of S. aureus. Randomized, controlled trials have shown that combination therapy with an antistaphylococcal penicillin and either gentamicin or rifampin does not improve outcomes and is associated with adverse events; therefore, this combination is not recommended. Daptomycin or vancomycin monotherapy is recommended for treatment of native-valve infective endocarditis caused by methicillin-resistant S. aureus. The benefit of combination therapy remains unproved. Combination therapy is recommended for the treatment of enterococcal infective endocarditis.