Prevention of Bacterial Endocarditis

Dental treatment, surgical procedures, or instrumentation involving mucosal surfaces or contaminated tissue may cause transient bacteremia. Blood-borne bacteria may lodge on damaged or abnormal heart valves or on endocardium near congenital anatomic defects and result in bacterial endocarditis or endarteritis. However, it is impossible to predict which patients will develop this infection or which procedures will be responsible. Therefore, prophylactic antibiotics are recommended for patients at risk who are undergoing those procedures most likely to cause bacteremia. It is important that such antibiotics be initiated shortly before, not several days before, a procedure. Certain patients, for example those with prosthetic heart valves and surgically constructed systemic-pulmonary shunts or conduits, are at higher risk of endocarditis than others (Table 1). Likewise, certain dental (eg, extractions) and surgical (eg, genitourinary tract) procedures are much more likely to initiate significant bacteremia than are others (Table 2). Although the importance of such factors is difficult to quantitate, they have been considered in developing these recommendations. Because there are no controlled clinical trials, the choice of antibiotic regimens for prevention of endocarditis in humans must be based on indirect information. The present recommendations are based upon a review of available data, including in vitro studies, clinical experience, experimental animal model data, and assessment of both the bacteria most likely to produce bacteremia from a given site and those most likely to result in endocarditis. The substantial morbidity and mortality in infective endocarditis and the paucity of controlled clinical studies emphasize the need for continuing research into the epidemiology, pathogenesis, prevention, and therapy of endocarditis.