NEW ORLEANS — Two minutes of toothbrushing commonly produces bacteremia involving a similar spectrum of infective endocarditis-causing pathogens as tooth extraction, Peter B. Lockhart, D.D.S., reported at the annual scientific session of the American College of Cardiology.
This new finding from a randomized, controlled trial suggests that brushing teeth may represent a far greater risk for infective endocarditis than the office dental procedures for which at-risk individuals are regularly prescribed prophylactic antibiotics. After all, people brush their teeth hundreds of times per year, resulting in far greater cumulative exposure to bacteremia, added Dr. Lockhart of the Carolinas Medical Center, Charlotte, N.C.
He reported on 290 patients in need of a dental extraction, which is considered to be the most invasive dental procedure and therefore the one most likely to produce bacteremia.
The subjects were randomized to extraction 1 hour following prophylactic amoxicillin, extraction with placebo, or 2 minutes of teeth brushing using a new toothbrush. Six venous blood draws were obtained from each participant starting 1 hour before the oral surgery or hygienic brushing, with the final sample being drawn 60 minutes after the end of the procedure. All of the bacterial isolates under- went genetic sequencing for species identification.
Bacteremia arising from toothbrushing was a common event, not entirely surprising given that brushing the teeth disrupts a much larger surface area of gingival tissue than a tooth extraction, Dr. Lockhart noted.
The overall incidence of bacteremia was 32% in the toothbrushing group, 56% in the extraction-plus-amoxicillin group, and 80% for extraction with placebo. Thus, amoxicillin prophylaxis was significantly more effective than placebo.
A total of 127 different bacterial species were identified, by far the most common being the viridans streptococci.
Dr. Patrick T. O'Gara commented that this study challenges traditional thinking regarding empiric antibiotic prophylaxis for dental procedures in patients at risk for infective endocarditis.
“Our thinking should change regarding the efficacy and need for antibiotic prophylaxis,” he declared.
“Why should prophylaxis be provided for extractions only, if the cumulative risk of toothbrushing is actually higher? It wouldn't seem feasible or appropriate that we instructed our patients to use antibiotics each time they brush their teeth,” added Dr. O'Gara, director of clinical cardiology and vice-chairman of medicine for clinical affairs at Brigham and Women's Hospital, Boston.
The study provides a mechanism that explains a phenomenon many clinicians have observed: namely, that it's far more common for patients with viridans streptococci endocarditis to not have a history of a recent trip to the dentist than to have such a history, he added.
A key implication of Dr. Lockhart's study, Dr. O'Gara continued, is the need to stress to patients at risk for infective endocarditis the importance of practicing meticulous dental and oral hygiene. The goal in doing so is to reduce their cumulative risk of bacteremia generated by daily home-based tooth and gum care.
Since the presentation of these results, the American Heart Association has issued revised guidelines on prophylactic antibiotics (see accompanying story). Dr. Lockhart was a member of the writing committee, and Dr. O'Gara was a reviewer.
Streptococcus viridans causes about half of all cases of bacterial endocarditis, but is also part of the mouth's normal bacterial flora. CDC/Dr. Mike Miller