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New Guidelines for Antibiotic Prophylaxis of Endocarditis
Abstract & Commentary
By Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford University; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center. Dr. Deresinski serves on the speaker's bureau for Merck, Pharmacia, GlaxoSmithKline, Pfizer, Bayer, and Wyeth, and does research for Merck.
This article originally appeared in the June 2006 issue of Infectious Disease Alert. It was peer reviewed by Connie Price, MD. Dr. Price is Assistant Professor, University of Colorado School of Medicine. She reports no financial relationships relevant to this field of study.
Synopsis: The new guidelines recommend antibiotic prophylaxis of infective endocarditis in a much more restricted group of patients than did previous guidelines.
Source: Wilson W, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. A guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation. 2007; April 19: [Epub ahead of print].
The American Heart Association last published guidelines on the use of antibiotic prophylaxis for the prevention of infective endocarditis in 1997.1 Those guidelines were quite complex, characterizing patients as having high, moderate, and low risk of infection, and including recommendations for all but the low-risk group, undergoing a variety of dental, respiratory, genitourinary, and gastrointestinal procedures. These guidelines have remained in place since that time, and are included in the latest (2007) Sanford guide.2 They cast a very wide net, leading to very frequent use of antibiotic prophylaxis in a large number of patients. In addition, it has been my experience that, in practice, the use of antibiotic prophylaxis has become the default position, so that it is administered to many patients despite their not meeting the broad criteria of the 1997 guidelines. Despite the guidelines and the even more expansive practice, skepticism has been expressed regarding the benefit of antibiotic prophylaxis in many circumstances. In this regard, included along with the 2007 Sanford guide recommendations is a caveat that at least one study "brings into serious question whether dental procedures predispose to endocarditis and whether antibiotic prophylaxis is of any value."
This skepticism is based on a number of factors, including the lack of any randomized clinical trial demonstrating efficacy of prophylaxis of endocarditis — the large number of individuals required for such a study make it likely that no sufficiently powered trial to definitively answer the question will ever be performed. Furthermore, as outlined by Wilson and colleagues in the 2007 guideline, which has been endorsed by the Infectious Disease Society of America, "infectious endocarditis is much more likely to result from frequent exposure to random bacteremias associated with daily activities than from bacteremia caused by a dental, GI tract, or GU tract procedure."
For instance, it has been estimated that twice daily tooth brushing for one year entails a risk of bacteremia that is 154,000 times greater than the risk of exposure resulting from a single tooth extraction. As a consequence, if antibiotics given in relation to these procedures are capable of preventing infective endocarditis, the number of such cases prevented is likely to be "exceedingly small" and, taking into account the potential adverse effects of antibiotic use on the individual and the general bacterial ecology, such use should be limited. It is estimated that, while the risk of endocarditis associated with a dental procedure is, eg, 1.1 per million procedures in a patient with mitral valve prolapse, the incidence of fatal anaphylaxis after penicillin administration is 15-25 per million. Finally, the effective maintenance of good oral hygiene, by reducing the frequency and intensity of bacteremia associated with daily activities, is the most effective means of endocarditis risk reduction.
Taking these factors into account, the new guidelines do not recommend antibiotic prophylaxis for endocarditis prevention for almost all individuals undergoing procedures other than certain high-risk dental procedures. Thus, antibiotic prophylaxis is recommended for individuals undergoing dental procedures that involve manipulation of gingival tissue, or the periapical region of teeth, or perforation of the oral mucosa, as well as for individuals undergoing surgical procedures on infected skin, skin structure or muscle, or incision of respiratory tract mucosa, and who have one of the following cardiac conditions:
Among the dental procedures for which antibiotic prophylaxis is not indicated include "routine anesthetic injections through noninfected tissue, taking dental radiographs, placement of removable prosthodontic or orthodontic appliances, adjustment of orthodontic appliances, placement of orthodontic brackets, shedding of deciduous teeth, and bleeding from trauma to the lips or oral mucosa." Prophylaxis is not indicated for individuals undergoing genitourinary or gastrointestinal procedures, including endoscopy. Actual site infections should, of course, be appropriately treated.
The recommended, orally-administered regimen for most adults for whom dental prophylaxis is indicated is a single 2 gram dose of amoxicillin 30 to 60 minutes before the procedure. In patients with a history of allergy to penicillins, a single 600 mg dose of clindamycin may be given. Alternatively, if the allergic manifestation was other than anaphylaxis, angioedema, or urticaria, a single 2 gram dose of cephalexin may be administered. If oral administration is not possible, parenterally-administered alternatives include ampicillin (2 grams IV or IM), cefazolin (1 gram IV or IM), ceftriaxone (1 gram IV or IM), or clindamycin 600 mg IV or IM). Recommended pediatric regimens are also provided.
"The Committee… recognizes that these new recommendations may cause concern among patients who have previously received antibiotic prophylaxis to prevent infective endocarditis before dental or other procedures and are now advised that such prophylaxis is unnecessary." It is likely that many health care providers will also be made anxious.
1. Dajani AS, et al. Prevention of bacterial endocarditis. Recommendations by the American Heart Association. JAMA. 1997;277:1794-1801.
2. The Sanford Guide to Antimicrobial Therapy, 2007:162.