title: Gram-positive cocci are associated with the formation of completely pure cholesterol stones.
abstract: OBJECTIVE
  Recently it has been reported that bacterial DNA has been detected in mixed cholesterol stones (cholesterol content < 95%), which were not previously believed to be related to bacteria, using the polymerase chain reaction (PCR). We examined bacterial DNA in pure cholesterol stones to clarify the mechanism of initiation or promotion of the formation of cholesterol gallstones.
  
  
  METHODS
  We examined 69 gallstones (30 brown pigment stones, 21 pure cholesterol stones, and 18 mixed cholesterol stones). Bacterial DNA was extracted from the core of the gallstones and amplified by PCR. Bacteria species in gallstones were identified by DNA sequencing of the PCR products.
  
  
  RESULTS
  Bacterial DNA was detected in 26/30 brown pigment stones (87%), in 12/21 pure cholesterol stones (57%) (cholesterol content = 100%), and in 12/18 mixed cholesterol stones (67%) (cholesterol content = 82-95%). Bacterial species in gallstones were identified by DNA sequencing of PCR products. Eighty percent of bacteria in brown pigment stones were gram-negative rods or anaerobes. In contrast, 100% of bacteria in pure cholesterol stones were gram-positive cocci. The bacteria in mixed cholesterol stones consisted of 40% gram-positive cocci, 50% gram-negative rods, and 10% anaerobes.
  
  
  CONCLUSIONS
  It was strongly suggested that gram-positive cocci are associated with the formation of pure cholesterol stones.
authors.affiliation: Second Department of Surgery, Wakayama Medical University, School of Medicine, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Kawai
authors.forename: Makoto
authors.initials: M
authors.lastname: Iwahashi
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Uchiyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Ochiai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanimura
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamaue
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D002769:Cholelithiasis / Q000737:chemistry* / Q000382:microbiology*; D002784:Cholesterol / Q000737:chemistry*; D004269:DNA, Bacterial / Q000032:analysis*; D005260:Female; D006095:Gram-Positive Cocci / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial; D002784:Cholesterol