These microorganisms may cause intra-abdominal infection or infection of the hepatobiliary system. Such infections are often polymicrobial, with a mix of aerobic and anaerobic Gram-negative and Gram- positive microorganisms, but among these varied bacteria, only enterococci are likely to cause IE. Enterococci may cause urinary Table 5. Regimens for a Dental Procedure Situation Agent Regimen: Single Dose 30 to 60 min Before Procedure Adults Children Oral Amoxicillin 2 g 50 mg/kg Unable to take oral medication Ampicillin OR Cefazolin or ceftriaxone 2 g IM or IV 1 g IM or IV 50 mg/kg IM or IV 50 mg/kg IM or IV Allergic to penicillins or ampicillin oral Cephalexin* OR Clindamycin OR Azithromycin or clarithromycin Allergic to penicillins or ampicillin and unable to take oral medication Cefazolin or ceftriaxone OR Clindamycin 1 g IM or IV 600 mg IM or IV 50 mg/kg IM or IV 20 mg/kg IM or IV IM indicates intramuscular; IV, intravenous. *Or other first- or second-generation oral cephalosporin in equivalent adult or pediatric dosage. Cephalosporins should not be used in an individual with a history of anaphylaxis, angioedema, or urticaria with penicillins or ampicillin. Wilson et al Prevention of Infective Endocarditis 1747 tract infections, particularly in older males with prostatic hypertro- phy and obstructive uropathy or prostatitis. The administration of prophylactic antibiotics solely to pre- vent endocarditis is not recommended for patients who undergo GU or GI tract procedures, including diagnostic esopha- gogastroduodenoscopy or colonoscopy (Class III, LOE B). This is in contrast to previous AHA guidelines that listed GI or GU tract procedures for which IE prophylaxis was recommended and those for which prophylaxis was not recommended.1 A large number of diagnostic and therapeutic procedures that involve the GI, hepatobiliary, or GU tract may cause transient enterococcal bacteremia. 