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Heart. 2007 June; 93(6): 753–754.
PMCID: PMC1955218

Antimicrobial prophylaxis for endocarditis: emotion or science?

The authors reply: Our editorial1 was designed to provoke debate and alert cardiologists, many of whom were unaware, of the publication of the British Society for Antimicrobial Chemotherapy guidelines. Despite the comments made by the respondents, we believe that most will agree that endocarditis is a severe disease, that the microbiological epidemiology is not just limited to dental procedures and that there is no robust proof of the efficacy or non‐efficacy of antibiotic prophylaxis.

The unwanted effects of antibiotics are often dismissed by protagonists of dental prophylaxis; however, the risk of death from penicillin anaphylaxis is 20 per million.2,3 A recent cost‐effectiveness analysis showed that in a cohort of 10 million moderate‐ or high‐risk people, penicillin would prevent 19 cases of endocarditis but cause 181 deaths due to anaphylaxis.4

We agree that clinical experience is important in determining individual patient management; however, it is not a substitute for appropriately obtained evidence from experimental and clinical trials when preparing clinical guidelines. A trained, experienced and impartial person can sift and weigh the evidence and reach a valid conclusion. In this circumstance, clinical experience and knowledge of the severe effects of endocarditis should not be an over‐riding influence.

One respondent attempts a cost analysis. Comparing a single dose of 3 g amoxicillin (£5.85, $11.39, €8.57)5 with prolonged parenteral antibiotics, complex surgery and high morbidity, he concludes that the prophylactic antibiotics are cheaper. This is simplistic since it ignores vast differences in the numbers treated in the two groups. Moreover, an effectiveness analysis clearly shows that penicillin kills more people than it saves because although anaphylaxis is rare the exposure to penicillin is potentially very large.

In this situation clinical discretion is of paramount importance. We must discuss the benefits and risks of the treatments offered. Simply saying “Take this antibiotic, it will protect you from endocarditis” is not enough. The benefits of prophylaxis are greater in high‐risk patients (those with prosthetic valves, previous infective endocarditis, congenital cyanotic heart disease) and relatively small in low‐risk groups such as patients with mitral valve prolapse. Unsurprisingly, the Microbiology Specialist Advisory Group working party is not the first to reach these conclusions. The French Recommendations published in 2002 in Heart also recommended maintaining the principle of prophylaxis but limiting it to patients with the highest ratio of individual benefit.6


1. Ashrafian H, Bogle R G. Antimicrobial prophylaxis for endocarditis: emotion or science? Heart 2007. 935–6.6 [PMC free article] [PubMed]
2. Idsoe O, Guthe T, Willcox R. et al Nature and extent of penicillin side‐reactions, with particular reference to anaphylactic shock. Bull World Health Organ 1968. 38159–188.188 [PubMed]
3. Ahlstedt S. Penicillin allergy: can the incidence be reduced? Allergy 1984. 39151–164.164 [PubMed]
4. Agha Z, Lofgren R P, VanRuiswyk J V. Is antibiotic prophylaxis for bacterial endocarditis cost‐effective? Med Decis Making 2005. 25308–320.320 [PubMed]
5. Department of Health Electronic drug tariff. (accessed 5 Mar 2007)
6. Danchin N, Duval X, Leport C. Prophylaxis of infective endocarditis: French Recommendations 2002. Heart 2005. 91715–718.718 [PMC free article] [PubMed]

Articles from Heart are provided here courtesy of BMJ Publishing Group