Prophylaxis for infective endocarditis. Who needs it? How effective is it?

To review guidelines for using antibiotic prophylaxis to prevent infective endocarditis, and to present recent changes and controversies regarding these guidelines. Data are from physiologic and in vitro studies, as well as studies of animal models, and from retrospective analyses of human endocarditis cases. Systematic reviews and guidelines are also examined. As no randomized clinical trials have examined prophylaxis for bacterial endocarditis, many recommendations presented are based on consensus guidelines. Antibiotic prophylaxis to prevent bacterial endocarditis should be used in high- and moderate-risk patients with cardiac disease. It should be given before procedures in which bacteremias are likely with organisms that cause endocarditis, such as viridans streptococci. For most procedures, a single dose of amoxicillin (2 g by mouth 1 hour before the procedure) is sufficient to ensure adequate serum levels before and after the procedure. Infective endocarditis continues to have high rates of morbidity and mortality. Antibiotic prophylaxis, therefore, is important to combat this preventable disease. For high- and moderate-risk patients with cardiac disease, the cost-benefit ratio favours prophylaxis.