title: Enteropathogenic Escherichia coli strain RDEC-1 produces a novel electrogenic factor active on rabbit ileum in vitro.
abstract: BACKGROUND
  Attaching and effacing Escherichia coli demonstrate marked species specificity in inducing diarrhea, although its mechanism remains largely unclear. The purpose of this study was to investigate the existence of a soluble, species-specific factor that induces diarrhea in an in vitro model.
  
  
  METHODS
  Stripped rabbit ileum was mounted in Ussing chambers, and changes in potential difference and short-circuit current were monitored after the addition of bacterial culture supernatant.
  
  
  RESULTS
  The culture supernatant from rabbit-specific strain RDEC-1, but not from human-specific enteropathogenic Escherichia coli strain E2348/69, induced an increase in potential difference and short-circuit current in rabbit ileum mounted in Ussing chambers. This electrical signal was related to chloride ion secretion, was absent in colonic tissue, and was retained in the 30 to 100-KDa fraction of the supernatant. Preliminary experiments failed to show an involvement of calcium or cyclic nucleotides as intracellular messengers. RDEC-1 cured of a 42-MDa plasmid lost the enterotoxicity whereas conjugation of the plasmid into the negative E. coli recipient HB101 resulted in the expression of toxicity.
  
  
  CONCLUSIONS
  The authors describe a novel, species-specific factor that helps to explain RDEC-1 diarrhea, which may be relevant to the pathogenesis of enteropathogenic Escherichia coli infection.
authors.affiliation: Dipartimento di Pediatria, Universitá Federico II, Naples, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Raimondi
authors.forename: J B
authors.initials: JB
authors.lastname: Kaper
authors.forename: E C
authors.initials: EC
authors.lastname: Boedeker
authors.forename: M K
authors.initials: MK
authors.lastname: Wolf
authors.forename: S
authors.initials: S
authors.lastname: Guandalini
authors.forename: A
authors.initials: A
authors.lastname: Fasano
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism; D046508:Culture Techniques; D003967:Diarrhea / Q000209:etiology / Q000382:microbiology*; D004553:Electric Conductivity; D004768:Enterotoxins / Q000096:biosynthesis; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000503:physiopathology; D007082:Ileum / Q000382:microbiology*; D008564:Membrane Potentials; D008970:Molecular Weight; D011817:Rabbits; D013045:Species Specificity
chemical_list: D002712:Chlorides; D004768:Enterotoxins