title: Tonsillolith: not just a stone but a living biofilm.
abstract: OBJECTIVE
  To study the morphology and activity of tonsilloliths, demonstrating oxygen respiration, denitrification, and acidification on exposure to sucrose.
  
  
  METHODS
  Tonsilloliths were extracted in atraumatic conditions during tonsillectomy from 16 adults and sent to two different laboratories for histological, bacteriological, and biofilm studies under sterile conditions.
  
  
  METHODS
  Multicenter laboratory study.
  
  
  METHODS
  Multiple tonsilloliths from two patients examined by confocal microscopy and microelectrodes were used to measure aerobic/anaerobic respiration and acid production (dissolved oxygen, nitrous oxide, pH) when exposed to saliva following addition of sucrose and fluoride.
  
  
  RESULTS
  Morphologically, tonsilloliths were similar to dental biofilms, containing corncob structures, filaments, and cocci. Microelectrodes showed that the microorganisms respired oxygen and nitrate. The oxygen concentration in the center of the tonsillolith was depleted to approximately one-tenth of that of the overlying fluid. The addition of sucrose resulted in acid production within the tonsillolith, dropping the pH from 7.3 to 5.8. The data showed stratification with oxygen respiration at the outer layer of tonsillolith, denitrification toward the middle, and acidification toward the bottom. The depletion of oxygen and acid production following addition of sucrose may allow the proliferation of anaerobic/acidophilic bacteria. Fluoride suppressed acid production in the presence of sucrose.
  
  
  CONCLUSIONS
  Tonsilloliths exhibit biofilm structure and the formation of chemical gradients through physiological activity. Although tonsillectomy is an option for treating cryptic infections, understanding the morphology and biofilm characteristics of tonsilloliths may stimulate scientists to use limited or targeted remedies in the future.
authors.affiliation: Center for Genomic Science, Allegheny-Singer Research Institute, Pittsburgh, PA, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stoodley
authors.forename: Dirk
authors.initials: D
authors.lastname: Debeer
authors.forename: Mark
authors.initials: M
authors.lastname: Longwell
authors.forename: Laura
authors.initials: L
authors.lastname: Nistico
authors.forename: Luanne
authors.initials: L
authors.lastname: Hall-Stoodley
authors.forename: Bruce
authors.initials: B
authors.lastname: Wenig
authors.forename: Yosef P
authors.initials: YP
authors.lastname: Krespi
mesh_terms: D000328:Adult; D001421:Bacteria, Anaerobic / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D002137:Calculi / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008839:Microelectrodes; D018613:Microscopy, Confocal; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D014066:Palatine Tonsil / Q000382:microbiology* / Q000473:pathology; D010608:Pharyngeal Diseases / Q000175:diagnosis* / Q000601:surgery; D014068:Tonsillectomy
chemical_list: D010100:Oxygen