From the Guidelines
Infective endocarditis is a serious infection of the endocardium, the inner lining of the heart chambers and valves, caused by microorganisms, typically bacteria or fungi, with a complex pathophysiology involving damage to the endocardial surface, microbial attachment, and formation of infected vegetations. The pathophysiology begins with damage to the endocardial surface, creating a favorable environment for microbial attachment, which may result from turbulent blood flow due to structural heart abnormalities, prosthetic valves, or intravenous catheters 1. Once the endothelium is damaged, platelets and fibrin deposit on the surface, forming sterile vegetations, and if bacteremia occurs, microorganisms can adhere to these vegetations, multiply, and form infected vegetations.
Key Aspects of Infective Endocarditis
- Common causative organisms include Staphylococcus aureus, viridans streptococci, enterococci, and HACEK organisms 1.
- The growing vegetations can lead to valve destruction, heart failure, and systemic embolization.
- The infection triggers an immune response with elevated inflammatory markers, and microorganisms can release toxins that further damage cardiac tissue.
- Risk factors include intravenous drug use, prosthetic heart valves, previous endocarditis, congenital heart disease, and recent dental or invasive procedures.
Clinical Considerations
The disease can be acute or subacute, with the latter having a more indolent course but both potentially leading to serious complications if not promptly diagnosed and treated with appropriate antibiotics 1. The epidemiology of infective endocarditis has become more complex with today’s myriad healthcare-associated factors that predispose to infection, and changes in pathogen prevalence, in particular a more common staphylococcal origin, have affected outcomes. Prompt diagnosis and treatment are crucial to improve morbidity, mortality, and quality of life outcomes in patients with infective endocarditis.
From the Research
Definition of Infective Endocarditis
Infective endocarditis is one of the most difficult-to-treat infectious diseases 2. It is caused by bacteria such as staphylococci, streptococci, enterococci, and Gram-negative bacilli, including HACEK 2.
Pathophysiology of Infective Endocarditis
The pathophysiology of infective endocarditis involves the colonization of microorganisms on the heart valves, leading to inflammation and damage to the valve tissue. This can result in complications such as heart failure, embolism, and arrhythmias.
Treatment of Infective Endocarditis
The treatment of infective endocarditis typically involves antibiotics, with the specific regimen depending on the causative organism and the patient's clinical condition. Some common antibiotic regimens include:
- Aqueous penicillin G alone for four weeks or combined with streptomycin for two weeks for penicillin-sensitive viridans or nonenterococcal group D streptococcal endocarditis 3
- A combination of aqueous penicillin G and either streptomycin or gentamicin for four to six weeks for enterococcal endocarditis 3
- Semisynthetic penicillin or cephalosporin for four to six weeks for Staphylococcus aureus endocarditis 3
- Ceftriaxone once daily for four weeks compared with ceftriaxone plus gentamicin once daily for two weeks for treatment of endocarditis due to penicillin-susceptible streptococci 4
- Outpatient continuous-infusion benzylpenicillin combined with either gentamicin or ceftriaxone for enterococcal endocarditis 5
- Penicillin-gentamicin and dual beta-lactam therapies for Enterococcus faecalis infective endocarditis 6
Key Considerations
Some key considerations in the treatment of infective endocarditis include:
- The use of aminoglycosides, such as gentamicin, should be limited to no more than two weeks due to the risk of nephrotoxicity 2
- The optimal duration of antibacterial treatment is four weeks for most native valve endocarditis and six weeks for prosthetic-valve endocarditis 2
- The oral switch is safe in patients stabilized after the initial intravenous course 2
- Dual beta-lactam therapy with ampicillin and ceftriaxone may provide a tolerable and equally efficacious option for treatment of Enterococcus faecalis infective endocarditis 6