Continuing controversy

Sir, the NICE guidance does not recommend any antibiotic prophylaxis, even for dental procedures in patients with high risk cardiac lesions¹ and correspondence from Martin clearly supports this approach.² However, the American Heart Association (AHA) reviewed similar scientific literature to that considered by NICE and does recommend prophylaxis for high risk cardiac patients.³

Martin is correct to state that endocarditis is unlikely to follow a single dental procedure but this does not necessarily mean there is no risk. An analogy can be made with hip joint replacement surgery where it is unlikely that postoperative deep sepsis will occur, but nonetheless the consequences of such infection may be catastrophic when it does happen. Streptococcal endocarditis in a patient with a prosthetic heart valve, an example of a high risk cardiac condition, may well result in death.

The NICE guidelines, and Martin, refer to tooth brushing as a risk but there is no direct evidence that this has ever caused endocarditis. Also, toothbrushing generally causes significant viridans streptococcal bacteraemia only when severe periodontitis is present.⁴ There is compelling indirect evidence for the importance of dental extractions as both a cause of highly predictable streptococcal bacteraemia and of occasional cases of viridans streptococcal endocarditis.⁴ Extractions, and surgery involving the gums or teeth, continue to warrant antibiotic prophylaxis against endocarditis for patients with high risk cardiac conditions, as recommended by the latest AHA report.³

Martin is not correct to state there is no evidence that amoxicillin would be effective for prophylaxis.² It would be more accurate to note that there is no controlled clinical trial data on the efficacy of amoxicillin for preventing endocarditis after dental procedures, partly because of the rarity of the disease. However, there is strong evidence that shows a single dose of amoxicillin can be highly effective in preventing streptococcal endocarditis in a stringent experimental animal model.⁴ There is markedly conflicting data from different bacteraemia studies and some of this may arise from different blood culture methods used.^4,5

The NICE guidance suggests that the risk of fatal anaphylaxis from amoxicillin prophylaxis is so great that it would result in more deaths from anaphylaxis than the number of endocarditis deaths prevented by giving amoxicillin prophylaxis. However, this fear is probably exaggerated as there have been no reports of deaths from anaphylaxis following amoxicillin prophylaxis against endocarditis, either in America² or the UK.⁶