title: Microbiological evaluation of acute periradicular abscesses by DNA-DNA hybridization.
abstract: OBJECTIVE
  The purpose of the present investigation was to examine the microbiota of acute periradicular abscesses of endodontic origin by using a molecular genetic method.
  
  
  METHODS
  Pus was collected by aspiration from 27 cases diagnosed as acute abscesses of endodontic origin, and DNA was extracted to evaluate the occurrence of 49 bacterial species by using whole genomic DNA probes and checkerboard DNA-DNA hybridization. The presence of bacterial DNA in clinical samples was confirmed by polymerase chain reaction with ubiquitous bacterial 16S rRNA gene primers.
  
  
  RESULTS
  The results of the checkerboard DNA-DNA hybridization analysis revealed that 37 of the 49 DNA probes tested were reactive with one or more samples. The number of bacterial species in the pus samples ranged from 1 to 33 (mean, 5.9). Eighteen of the 27 pus samples were positive for at least one DNA probe. The most prevalent species found were: Bacteroides forsythus (29.6% of the cases); Porphyromonas gingivalis (29.6%); Streptococcus constellatus (25.9%), Prevotella intermedia (22.2%), Prevotella nigrescens (22.2%), Fusobacterium periodonticum (18.5%), Fusobacterium nucleatum subspecies nucleatum (18.5%), and Eikenella corrodens (18.5%).
  
  
  CONCLUSIONS
  The microbiologic data of the present investigation indicated that molecular genetic methods could provide additional knowledge regarding the microbiota of acute periradicular abscesses by detecting bacterial species that are difficult--or even impossible--to grow.
authors.affiliation: Oral Microbiology Laboratory, Institute of Microbiology, Federal University of Rio de Janeiro, 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: R
authors.initials: R
authors.lastname: Souto
authors.forename: M
authors.initials: M
authors.lastname: Uzeda
authors.forename: A P
authors.initials: AP
authors.lastname: Colombo
mesh_terms: D000328:Adult; D001421:Bacteria, Anaerobic / Q000235:genetics; D015373:Bacterial Typing Techniques; D015342:DNA Probes; D004269:DNA, Bacterial / Q000032:analysis; D006801:Humans; D009693:Nucleic Acid Hybridization / Q000379:methods; D010482:Periapical Abscess / Q000382:microbiology*; D016133:Polymerase Chain Reaction
chemical_list: D015342:DNA Probes; D004269:DNA, Bacterial