The Committee believes that a single dose of amoxicillin or ampicillin is safe and is the preferred prophy- lactic agent for individuals who do not have a history of type I hypersensitivity reaction to a penicillin, such as anaphy- laxis, urticaria, or angioedema. Fatal anaphylaxis from a cephalosporin is estimated to be less common than from penicillin, at approximately 1 case per 1 million patients.95 Fatal reactions to a single dose of a macrolide or clindamycin are extremely rare.96,97 There has been only 1 case report of documented Clostridium difficile colitis after a single dose of Summary Although it has long been assumed that dental procedures may cause IE in patients with underlying cardiac risk factors and that antibiotic prophylaxis is effective, scientific proof is lacking to support these assumptions. The collective pub- lished evidence suggests that of the total number of cases of IE that occur annually, it is likely that an exceedingly small number are caused by bacteremia-producing dental proce- dures. Accordingly, only an extremely small number of cases of IE might be prevented by antibiotic prophylaxis even if it were 100% effective. The vast majority of cases of IE caused by oral microflora most likely result from random bactere- mias caused by routine daily activities, such as chewing food, tooth brushing, flossing, use of toothpicks, use of water irrigation devices, and other activities. The presence of dental disease may increase the risk of bacteremia associated with these routine activities. There should be a shift in emphasis away from a focus on a dental procedure and antibiotic prophylaxis toward a greater emphasis on improved access to dental care and oral health in patients with underlying cardiac conditions associated with the highest risk of adverse out- come from IE and those conditions that predispose to the acquisition of IE. 