title: Bacteria in the apical root canals of teeth with apical periodontitis.
abstract: OBJECTIVE
  Bacteria in the tooth root canal may cause apical periodontitis. This study examined the bacterial species present in the apical root canal of teeth with apical periodontitis. Antibiotic sensitivity tests were performed to evaluate whether these identified bacterial species were susceptible to specific kinds of antibiotics.
  
  
  METHODS
  Selective media plating and biochemical tests were used first to detect the bacterial species in samples taken from the apical portion of root canals of 62 teeth with apical periodontitis. The isolated bacterial species were further confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry.
  
  
  RESULTS
  We found concomitant presence of two (32 teeth) or three species (18 teeth) of bacteria in 50 (80.6%) out of 62 tested teeth. However, only 34 bacterial species were identified. Of a total of 118 bacterial isolates (83 anaerobes and 35 aerobes), Prophyromonas endodontalis was detected in 10; Bacteroides, Dialister invisus or Fusobacterium nucleatum in 9; Treponema denticola or Enterococcus faecalis in 8; Peptostreptococcus or Olsenella uli in 6; and Veillonella in 5 teeth. The other 25 bacterial species were detected in fewer than five teeth. Approximately 80-95% of bacterial isolates of anaerobes were sensitive to ampicillin/sulbactam (Unasyn), amoxicillin/clavulanate (Augmentin), cefoxitin, and clindamycin. For E. faecalis, 85-90% of bacterial isolates were sensitive to gentamicin and linezolid.
  
  
  CONCLUSIONS
  Root canal infections are usually caused by a mixture of two or three species of bacteria. Specific kinds of antibiotic can be selected to control these bacterial infections after antibiotic sensitivity testing.
authors.affiliation: Department of Dentistry, Taipei City Hospital, Renai Branch, Taipei, Taiwan.
authors.forename: Li-Wan
authors.initials: LW
authors.lastname: Lee
authors.affiliation: Department of Dentistry, Taipei City Hospital, Heping Fuyou Branch, Taipei, Taiwan; Department of Dentistry, School of Dentistry, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Taipei City Hospital, Renai Branch, Taipei, Taiwan.
authors.forename: Sheng-Huang
authors.initials: SH
authors.lastname: Hsiao
authors.affiliation: Department of Dentistry, MacKay Memorial Hospital, Taipei, Taiwan; School of Dentistry, National Taiwan University, Taipei, Taiwan; School of Dentistry & Graduate Institute of Dental Sciences, China Medical University, Taichung, Taiwan. Electronic address: hungpin@gmail.com.
authors.forename: Hung-Pin
authors.initials: HP
authors.lastname: Lin
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003786:Dental Pulp Cavity / Q000382:microbiology*; D006801:Humans; D010485:Periapical Periodontitis / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents
keywords: antibiotic sensitivity test; apical periodontitis; bacterial species; root canal infection; teeth