title: Characterization of bacterial flora in persistent apical periodontitis lesions.
abstract: BACKGROUND
  Microorganisms are able to survive and induce persistent infection in periapical tissues. The aim of this study was to investigate the composition of the microflora of persistent apical periodontitis lesions.
  
  
  METHODS
  Twenty apical lesion samples were obtained from 20 patients with chronic apical periodontitis by root end surgery and processed using aerobic or anaerobic culture techniques. All isolated strains were identified by 16S ribosomal DNA sequence analysis.
  
  
  RESULTS
  Seventy-four strains were isolated, belonging to 31 bacterial species obtained from the 20 apical lesions that were isolated. The majority of the strains were facultative anaerobes (51.6%). Propionibacterium acnes, Staphylococcus epidermidis, Pseudomonas aeruginosa and Fusobacterium nucleatum were isolated from 16.2, 9.5, 6.8 and 5.4% of the samples, respectively. Fifteen samples harboured more than one species. The predominant association was P. acnes, S. epidermidis and F. nucleatum.
  
  
  CONCLUSIONS
  The microbiota of persistent apical periodontitis lesions is composed by diverse types of microorganisms with biofilm-forming capacity, including P. acnes, S. epidermidis and F. nucleatum.
authors.affiliation: Department of Endodontics, Pulp and Periapical Biology, Tokyo Dental College, Chiba, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Fujii
authors.forename: Y
authors.initials: Y
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Tokura
authors.forename: K-I
authors.initials: KI
authors.lastname: Nakagawa
authors.forename: K
authors.initials: K
authors.lastname: Okuda
authors.forename: K
authors.initials: K
authors.lastname: Ishihara
mesh_terms: D001421:Bacteria, Anaerobic / Q000235:genetics / Q000302:isolation & purification; D018441:Biofilms; D055113:Chronic Periodontitis / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D005260:Female; D016967:Fusobacterium nucleatum / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology*; D011425:Propionibacterium acnes / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D021521:Ribotyping; D013212:Staphylococcus epidermidis / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal