title: Metagenomic analysis of brain abscesses identifies specific bacterial associations.
abstract: BACKGROUND
  The bacterial flora involved in brain abscess is often complex. In a previous study, using a metagenomic approach based on 16S ribosomal DNA (rDNA) amplification, we demonstrated that the diversity of the microbial flora involved in these infections was underestimated.
  
  
  METHODS
  We performed a 16S rDNA-based metagenomic analysis of cerebral abscesses from patients diagnosed from 2006 through 2010. All bacteria present in brain abscess specimens were identified, in view of the clinical and epidemiological characteristics of the patients.
  
  
  RESULTS
  Fifty-one patients were included in our study. By detecting polymicrobial infections in 19 patients, our strategy was significantly more discriminatory and enabled the identification of a greater number of bacterial taxa than did culture and conventional 16S rDNA polymerase chain reaction (PCR) and sequencing, respectively (P < 10(-2)). Data mining discriminated 2 distinct bacterial populations in brain abscess from dental and sinusal origin. In addition, of the 80 detected bacterial species, we identified 44 bacteria that had never been found in brain abscess specimens, including 22 uncultured bacteria. These uncultured agents mostly originated from the buccal or sinusal floras (P < 10(-2)) and were found in polymicrobial specimens (P < 10(-2)).
  
  
  CONCLUSIONS
  Cloning and sequencing of PCR-amplified 16S rDNA is a highly valuable method to identify bacterial agents of brain abscesses.
authors.affiliation: Fédération de Microbiologie Clinique, Hôpital de la Timone, Marseille, France.
authors.forename: Mouhamad
authors.initials: M
authors.lastname: Al Masalma
authors.forename: Michel
authors.initials: M
authors.lastname: Lonjon
authors.forename: Hervé
authors.initials: H
authors.lastname: Richet
authors.forename: Henry
authors.initials: H
authors.lastname: Dufour
authors.forename: Pierre-Hugues
authors.initials: PH
authors.lastname: Roche
authors.forename: Michel
authors.initials: M
authors.lastname: Drancourt
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
authors.forename: Pierre-Edouard
authors.initials: PE
authors.lastname: Fournier
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D001922:Brain Abscess / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D054892:Metagenome / Q000235:genetics*; D056186:Metagenomics / Q000379:methods*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013492:Suppuration / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S