What characterizes acute infectious endocarditis?

From the Guidelines

Acute infective endocarditis is characterized by a rapid onset of infection affecting the heart valves or endocardial surface, typically developing over days to weeks, and is diagnosed using the modified Duke criteria, which include major and minor criteria such as positive blood cultures, evidence of endocardial involvement, and immunologic phenomena 1. The diagnosis of acute infective endocarditis is based on the presence of two major criteria, or one major and three minor criteria, or five minor criteria, as outlined in the modified Duke criteria 1. Some key features of acute infective endocarditis include:

• High fever (often >38°C)
• Chills
• Night sweats
• Fatigue
• Heart murmurs
• Positive blood cultures, with Staphylococcus aureus being the most common causative organism in acute cases, followed by group A streptococci and pneumococci
• Echocardiography often reveals vegetations on heart valves, which are collections of platelets, fibrin, microorganisms, and inflammatory cells
• Embolic phenomena (such as stroke, pulmonary emboli, or peripheral emboli)
• Immunologic manifestations (like Osler's nodes, Janeway lesions, and Roth spots)
• Elevated inflammatory markers (including leukocytosis, elevated C-reactive protein, and erythrocyte sedimentation rate) The most recent guidelines recommend empiric antibiotic therapy with vancomycin and ceftriaxone, adjusted based on culture results, followed by 4-6 weeks of targeted antibiotic therapy 1. Surgical intervention may be necessary for complications such as heart failure, uncontrolled infection, or prevention of embolic events. It's worth noting that the diagnosis and treatment of acute infective endocarditis should be guided by the most recent and highest quality evidence, and that the modified Duke criteria provide a useful framework for diagnosis 1. In terms of treatment, the American Heart Association recommends consultation with an infectious diseases specialist to define the most appropriate choice of therapy in patients with culture-negative endocarditis 1. Overall, the key to diagnosing and treating acute infective endocarditis is prompt recognition of the condition, based on the modified Duke criteria, and initiation of empiric antibiotic therapy, with adjustment based on culture results and consideration of surgical intervention as needed 1.

From the Research

Characteristics of Acute Infective Endocarditis

• Acute infective endocarditis is a complex disease with changing epidemiology and a rapidly evolving knowledge base 2
• It is characterized by a microbial infection of the endocardial surface of the heart 3
• The disease can be caused by various micro-organisms, including streptococci, staphylococci, enterococci, and Gram-negative bacilli, including HACEK 4
• The clinical team must have an understanding of the epidemiology, microbiology, and natural history of infective endocarditis, as well as a grasp of guiding principles of diagnosis and medical and surgical management 2

Microbiological Characteristics

• Streptococci or staphylococci cause 75% of cases of endocarditis 5
• Patients with penicillin-sensitive viridans or nonenterococcal group D streptococcal endocarditis may be treated successfully with aqueous penicillin G alone for four weeks or with combined penicillin and streptomycin for two weeks 5
• Enterococcal endocarditis should be treated for four to six weeks with a combination of aqueous penicillin G together with either streptomycin or gentamicin 5
• Patients with endocarditis caused by Staphylococcus aureus should receive antimicrobial therapy for four to six weeks with a semisynthetic penicillin (nafcillin or oxacillin) or a cephalosporin such as cephalothin or cefazolin 5

Treatment Characteristics

• Antibiotics are the cornerstone of treatment, but due to the differences in presentation, populations affected, and the wide variety of micro-organisms that can be responsible, their use is not standardized 3
• The optimal duration of antibacterial treatment is 4 weeks for most native valve endocarditis, and 6 weeks for prosthetic-valve endocarditis 4
• The oral switch is safe in patients stabilized after the initial intravenous course 4
• Limited and low to very low-quality evidence suggests that the comparative effects of different antibiotic regimens in terms of cure rates or other relevant clinical outcomes are uncertain 3