Identification of oral bacteria in blood cultures by conventional versus molecular methods

Objective. The purpose of this study was to compare two different methods of identifying oral bacteria from blood samples after dental extractions. Study design. Blood cultures were taken before, during, and after a single tooth extraction in 30 subjects and cultured using aerobic and anaerobic Bactec media. Positive cultures from 22 subjects were subcultured on selective and nonselective media, resulting in 58 isolates. Bacterial identification was performed by biochemical analysis and sequence analysis of 16S rRNA gene. Results. Of the 58 isolates, only 10 (17%) were the same species by both methods. Thirty-two (55%) belonged to the same genus but different species, and 16 (28%) showed no correlation at all. There were 31 and 40 diverse species by the biochemical and the sequencing methods, respectively. Streptococci were the dominant species. Conclusions. DNA sequencing results in more accurate identification and a more diverse population of bacteria from bacteremia following dental extractions.