Letter by Kaplan Regarding Article, “Bacteremia Associated With Toothbrushing and Dental Extraction”
To the Editor:
The recent paper entitled “Bacteremia Associated with Toothbrushing and Dental Extraction”1 addresses a topic of considerable clinical importance and, in ways, relates to the 2007 American Heart Association revised recommendations for antibiotic prophylaxis for prevention of bacterial endocarditis.2 The authors should be commended for undertaking this study, which must have been difficult to carry out; however, before these data can be put into appropriate perspective, several questions require thought.
(1) As stated in the Results section, the “higher percentage of complex extractions in the extraction-placebo group than in the extraction-amoxicillin group” suggests that the >60% of subjects with positive blood culture(s) in the placebo group may in fact be artifactually increased because of the more complex dental procedures. Therefore, those subjects probably experienced a “greater dose” of bacteria. Can the authors comment about this possibility?
(2) It would have been very interesting and possibly could have added to the significance of the study if the authors had made an effort to culture the “tooth socket” and then compared the recovered organisms with organisms recovered from blood cultures. Would this have been worthwhile in the authors’ opinion?
(3) I am surprised that the authors did not perform susceptibility testing of the organisms recovered from blood. With the wealth of information in the literature about antimicrobial resistance, susceptibility might have had a significant effect on whether blood cultures were positive in the treatment group, as well as providing some information about general susceptibility of mouth flora in the population.
(4) It also was surprising that the authors failed to consider a study by McGowan and colleagues3 in the study design. In that study, admittedly using an experimental rabbit model (described by Garrison and Freedman4), an impressive difference was found in the resulting bacteremia when a single dose of amoxicillin was used versus an initial amoxicillin dose and 1 subsequent dose. Despite the fact that a single dose of amoxicillin has been recommended for patients in the United Kingdom for some years (a few years less in the United States), wouldn’t this study have provided an ideal opportunity to generate more information as to whether a single dose is as efficacious in humans?
(5) It also would have been fascinating in this study to determine the antibiotic blood levels in the amoxicillin-extraction group. This was done in the McGowan study in rabbits, and the data were extremely interesting. More prolonged and higher amoxicillin serum levels were found in the 2-dose group. Because some of the human subjects in the present study had positive blood cultures several hours later (Figure 3 in the report by Lockhart et al1), it would be of interest to know what the amoxicillin blood levels actually were and to correlate this information with the ability to recover bacteria from the blood.
In summary, issues remain that perhaps might have made the data more applicable to the clinical scenario. I would like to know the authors’ thoughts on the above questions.
Lockhart PB, Brennan MT, Sasser HC, Fox PC, Paster BJ, Bahrani-Mougeot FK. Bacteremia associated with toothbrushing and dental extraction. Circulation. 2008; 117: 3118–3125.
Wilson W, Taubert KA, Gewitz M, Lockhart PB, Baddour LM, Levison M, Bolger A, Cabell CH, Takahashi M, Baltimore RS, Newburger JW, Strom BL, Tani LY, Gerber M, Bonow RO, Pallasch T, Shulman ST, Rowley AH, Burns JC, Ferrieri P, Gardner T, Goff D, Durack DT; American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee; American Heart Association Council on Cardiovascular Disease in the Young; American Heart Association Council on Clinical Cardiology; American Heart Association Council on Cardiovascular Surgery and Anesthesia; Quality of Care and Outcomes Research Interdisciplinary Working Group. Prevention of infective endocarditis: 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 [published correction appears in Circulation. 2007;116:e376–e377]. Circulation. 2007; 116: 1736–1754.