title: Direct amplification of rRNA gene sequences for identification of selected oral pathogens in root canal infections.
abstract: OBJECTIVE
  The purpose of this study was to assess the prevalence of selected oral pathogens in root canal infections and their relationship with symptoms using a highly sensitive technique, the polymerase chain reaction.
  
  
  METHODS
  Samples were obtained from 91 infected teeth associated with periradicular lesions, including cases of acute periradicular abscesses. DNA was extracted from the samples and analysed for the presence of target microbial species using a PCR-based identification assay.
  
  
  RESULTS
  All samples were positive for the presence of bacteria. Streptococcus anginosus group was detected in 16.7%, Fusobacterium nucleatum in 14.3%, and Bacteroides forsythus in 7.1% of the abscess samples. No pus sample yielded Actinomyces israelii, Actinobacillus actinomycetemcomitans or fungal species. In general, B. forsythus was found in 20% of the cases (16 of 80), S. anginosus in 12% (6 of 50), F. nucleatum in 10% (6 of 60) and A. israelii in 5% (two of 40). A. actinomycetemcomitans was not detected in any case. Fungi were present in only one of 50 cases (2%). There was no correlation between the species and symptoms.
  
  
  CONCLUSIONS
  Direct molecular approaches appear to be a valuable tool for the rapid and reliable diagnosis of infectious diseases, as well as for research purposes. There was no correlation between target microbial species and symptoms.
authors.affiliation: Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. siqueira@estacio.br
authors.forename: J F
authors.initials: JF
authors.lastname: Siqueira
authors.forename: I N
authors.initials: IN
authors.lastname: Rôças
authors.forename: S R
authors.initials: SR
authors.lastname: Moraes
authors.forename: K R N
authors.initials: KR
authors.lastname: Santos
mesh_terms: D000190:Actinomyces / Q000235:genetics; D000196:Actinomycosis / Q000175:diagnosis; D000328:Adult; D001439:Bacteroides / Q000145:classification / Q000235:genetics; D001442:Bacteroides Infections / Q000175:diagnosis; D016009:Chi-Square Distribution; D004269:DNA, Bacterial / Q000235:genetics; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003788:Dental Pulp Diseases / Q000382:microbiology*; D005674:Fusobacterium Infections / Q000175:diagnosis; D016967:Fusobacterium nucleatum / Q000235:genetics; D006801:Humans; D021141:Nucleic Acid Amplification Techniques; D016017:Odds Ratio; D010482:Periapical Abscess / Q000382:microbiology; D010483:Periapical Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000235:genetics*; D012335:RNA, Ribosomal / Q000235:genetics*; D013290:Streptococcal Infections / Q000175:diagnosis; D013291:Streptococcus / Q000145:classification / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012335:RNA, Ribosomal