Molecular detection of Enterococcus species in root canals of therapy-resistant endodontic infections

Objectives. The objectives were to identify Enterococcus spp in nonhealing endodontic cases using PCR amplification and molecular sequencing, and to determine if the prevalence of enterococci is increased in diabetic patients. Study design. Specimens from 40 cases undergoing retreatment were incubated in prereduced thioglycollate broth at 37degreesC. Extracted DNA had PCR amplification using primers that target the tuf gene of 14 Enterococcus spp. PCR products were directly sequenced and identified phylogenetically. Results. Three cases were eliminated because the patients were on antibiotics or the tooth did not have a periradicular radiolucency. The remaining 37 specimens included 6 from diabetic patients. Eight specimens were positive for Enterococcus spp. Of these, 6 (19%) were from nondiabetic and 2 (33%) from diabetic patients (odds ratio = 2.1; chi squared, P = .45). Phylogenetically, all sequences from positive specimens matched E faecalis V583 (AE016947). Conclusion. E faecalis was the only enterococcal species detected, with an overall prevalence of 22%.