Clinical Pearls & Morning Reports
Published June 30, 2021
Infective endocarditis is classified on the basis of the causative organism, affected valve, underlying valvular disease, presence of cardiac devices, and host risk factors. Read the NEJM Clinical Problem-Solving Article here.
Q: What laboratory findings may be seen in cases of infective endocarditis?
A: Nonspecific laboratory findings of immune activation, including polyclonal gammopathy, positive cryoglobulin testing, and hypocomplementemia, are common in infective endocarditis. Positivity on laboratory tests for rheumatoid factor, viral IgM antibodies, and venereal disease may arise because of circulating immune complexes and is more common in patients with symptoms lasting longer than 4 weeks, endocarditis on the right side of the heart, or extravalvular manifestations such as arthralgia, splenomegaly, Roth spots, or thrombocytopenia.
Q: What are some of the potential complications of a delay in the diagnosis of infective endocarditis?
A: A delay in diagnosing infective endocarditis can lead to heart failure and other complications, such as perivalvular abscesses, glomerulonephritis, or septic emboli resulting in strokes.
A: Although fever is a cardinal manifestation, it may be absent, particularly in older patients, in patients with previous antibiotic exposure, or in cases caused by organisms other than Staphylococcus aureus or viridans streptococci. Musculoskeletal symptoms are common and are the presenting symptom in 23 to 44% of all cases; these symptoms may be indicative of an osteoarticular infection. Over the past few decades, the incidence of infective endocarditis has shifted toward older persons, owing to longer life spans, an increase in the incidence of degenerative valve disease and the use of prosthetic valves, and a decrease in the incidence of rheumatic heart disease. However, the condition in more than two thirds of older patients is initially misdiagnosed, since musculoskeletal signs and symptoms are often attributed to aging or to rheumatologic conditions, and murmurs may be attributed to preexisting valvular disease.
A: Lactobacillus species are part of normal vaginal, gastrointestinal, and oral flora, yet their role as a colonizer or pathogen is debated. Positive blood cultures should be considered to represent true infection. Infective endocarditis due to lactobacillus is rare, preferentially affects the mitral valve, and may be associated with impaired immunity, structural heart disease, or dental procedures. In rare cases, it has been described in association with colonoscopy (although the procedure generally does not warrant antimicrobial prophylaxis), and several cases associated with probiotic use have also been reported. Although outcomes are usually favorable, extracardiac complications, including splenic abscesses, embolic strokes, and mycotic aneurysms have been described. Approximately 40% of patients with lactobacillus infective endocarditis do not have fever, and one third have weight loss.