title: Osteoradionecrosis contains a wide variety of cultivable and non-cultivable bacteria.
abstract: BACKGROUND
  Direct microscopy, anaerobic culture and DNA-DNA hybridization have previously demonstrated an association between microorganisms and osteoradionecrosis (ORN). The purpose of our study was to use culture independent molecular techniques to detect bacteria in necrotic bone lesions of the mandible after radiation therapy.
  
  
  METHODS
  Bacterial DNA was extracted from eight deep medullar specimens from resected mandibles (six cases), including one patient with relapse. 16S rRNA genes were PCR amplified, cloned, transformed into Escherichia coli and sequenced to determine species identity and closest relatives.
  
  
  RESULTS
  From the analysis of 438 clones, 59 predominant species were detected, 27% of which have not been cultivated. The predominant species detected from radionecrotic mandibles were Campylobacter gracilis, Streptococcus intermedius, Peptostreptococcus sp. oral clone FG014, uncultured bacterium clone RL178, Fusobacterium nucleatum, and Prevotella spp. The study demonstrated intersubject variability of the bacteria present in ORN. In contrast to the diverse bacterial profile detected in primary infection, only a few members of the oral indigenous flora were identified from the relapse case.
  
  
  CONCLUSIONS
  Diverse bacterial profiles in specimens of ORN in marrow spaces of the mandible were detected by culture independent molecular techniques. To better understand the pathogenesis and to improve the therapy of the infection, detection of all members of the complex bacterial flora associated with ORN is necessary.
authors.affiliation: Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Jørn A
authors.initials: JA
authors.lastname: Aas
authors.forename: Lars
authors.initials: L
authors.lastname: Reime
authors.forename: Kjetil
authors.initials: K
authors.lastname: Pedersen
authors.forename: Emenike R K
authors.initials: ER
authors.lastname: Eribe
authors.forename: Emnet
authors.initials: E
authors.lastname: Abesha-Belay
authors.forename: Geir
authors.initials: G
authors.lastname: Støre
authors.forename: Ingar
authors.initials: I
authors.lastname: Olsen