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. The possible association between GI or GU tract proce- dures and IE has not been studied as extensively as the possible association with dental procedures.145 The cases of IE temporally associated with a GI or GU tract proce- dure are anecdotal, with either a single or very small number of cases reported.83 No published data demonstrate a conclusive link between procedures of the GI or GU tract and the development of IE.145 Moreover, no studies exist that demonstrate that the administration of antimicrobial prophylaxis prevents IE in association with procedures performed on the GI or GU tract. There has been a dramatic increase in the frequency of antimicrobial-resistant strains of enterococci to penicillins, vanco- mycin, and aminoglycosides.146 151 These antibiotics were recom- mended for IE prophylaxis in previous AHA guidelines.1 The significance of the increased frequency of multiresistant strains of enterococci on prevention of IE in patients who undergo GI or GU tract procedures is unknown. The high prevalence of resistant strains of enterococci adds further doubt about the efficacy of prophylactic therapy for GI or GU tract procedures. Patients with infections of the GI or GU tract may have intermittent or sustained enterococcal bacteremia. 