title: Klebsiella oxytoca as an agent of antibiotic-associated hemorrhagic colitis.
abstract: OBJECTIVE
  Klebsiella oxytoca has been isolated from stools and colonic biopsy specimens of patients with Clostridium difficile-negative antibiotic-associated hemorrhagic colitis (AAHC), but the pathogenic role of the germ has not been established. The purpose of this study was to investigate the presence of K. oxytoca in patients with AAHC from a prospective cohort of patients with acute colitis, and to test the cytotoxicity on HEp-2 cells of K. oxytoca strains from patients with AAHC and healthy carriers.
  
  
  METHODS
  Colonic biopsy specimens and a sample of colonic fluid from 93 consecutive patients with acute colitis were cultured on selective media for 7 established pathogens and K. oxytoca. The 2 K. oxytoca strains isolated in the 4 patients with C. difficile-negative AAHC of this cohort and 105 additional K. oxytoca strains from patients with C. difficile-negative AAHC (n = 15) and healthy carriers (n = 90) were tested for cytotoxicity using a HEp-2 cell culture assay.
  
  
  RESULTS
  K. oxytoca was isolated in 50% (2 of 4) of the patients of the prospective cohort with C. difficile-negative AAHC compared with 2% (1 of 41) of the patients with acute colitis caused by established pathogens (P = 0.02). The rate of cytotoxic strains of K. oxytoca was higher in patients with AAHC (82%) than in healthy carriers (42%, P = 0.003).
  
  
  CONCLUSIONS
  We conclude that K. oxytoca is isolated with a significant high rate in patients with C. difficile-negative AAHC, and that K. oxytoca strains from patients with AAHC are cytotoxic more frequently on HEp-2 cells than strains from healthy carriers. These results strengthen the hypothesis of a causative role of K. oxytoca in some of the patients with AAHC.
authors.affiliation: Department of Gastroenterology, Saint-Antoine Hospital, 184 rue du faubourg Saint-Antoine, 75012 Paris, France. laurent.beaugerie@sat.ap-hop-paris.fr
authors.forename: Laurent
authors.initials: L
authors.lastname: Beaugerie
authors.forename: Michaela
authors.initials: M
authors.lastname: Metz
authors.forename: Frédéric
authors.initials: F
authors.lastname: Barbut
authors.forename: Guy
authors.initials: G
authors.lastname: Bellaiche
authors.forename: Yoram
authors.initials: Y
authors.lastname: Bouhnik
authors.forename: Laurent
authors.initials: L
authors.lastname: Raskine
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Nicolas
authors.forename: François-Patrick
authors.initials: FP
authors.lastname: Chatelet
authors.forename: Norbert
authors.initials: N
authors.lastname: Lehn
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Petit
mesh_terms: D000208:Acute Disease; D000328:Adult; D002478:Cells, Cultured; D004761:Enterocolitis, Pseudomembranous / Q000150:complications / Q000382:microbiology*; D005260:Female; D006471:Gastrointestinal Hemorrhage / Q000150:complications* / Q000382:microbiology; D006801:Humans; D007710:Klebsiella Infections / Q000150:complications* / Q000276:immunology; D041121:Klebsiella oxytoca / Q000502:physiology; D008297:Male; D008875:Middle Aged