Biomedicine

A Brush with Infection

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Science  27 Jun 2008:
Vol. 320, Issue 5884, pp. 1696
DOI: 10.1126/science.320.5884.1696b

The human mouth harbors a surprisingly diverse complement of bacteria. Although most are harmless, a subset—if they enter the bloodstream—are believed to cause a potentially life-threatening heart condition called infective endocarditis, especially in individuals with preexisting heart valve damage. For this reason, at-risk patients are often prescribed prophylactic antibiotics before invasive dental procedures such as tooth extraction. This practice has become increasingly controversial, however, both because of general concerns about the overuse of antibiotics and because the extent of bacteremia caused by tooth extraction has never been compared to that caused by other seemingly less traumatic activities, such as tooth brushing or mastication. Using 16S ribosomal RNA sequencing and quantitative polymerase chain reaction assays, Lockhart et al. profiled the bacteria in sequential blood samples drawn from patients who had undergone a tooth extraction with or without antibiotic treatment and from untreated patients who simply brushed their teeth. Thirty-two bacterial species that can cause infective endocarditis were identified in blood samples from patients after a tooth extraction and, as expected, antibiotic treatment significantly reduced their numbers. Surprisingly, brushing alone also caused a substantial increase in infective endocarditis-causing bacteria. Given that tooth brushing is a daily activity, the authors conclude that it could pose a risk for bacteremia comparable to that of a tooth extraction, thus underscoring the need for controlled clinical trials to evaluate current practices. — PAK

Circulation 117, 3118 (2008).

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