title: Glucose decreases virulence gene expression of Escherichia coli O157:H7.
abstract: Escherichia coli O157:H7 is responsible for a human toxico-infection that can lead to severe complications such as hemolytic uremic syndrome. Inside the intestine, E. coli O157:H7 forms typical attaching-effacing lesions and produces Shiga toxins. The genes that are responsible  for these lesions are located in a pathogenicity island called the locus of enterocyte effacement (LEE). LEE gene expression is influenced by quorum sensing through the luxS system. In this study, the effect of glucose on the expression of several genes from LEE, on the expression of  Shiga toxin genes, and on the expression of luxS was assessed with real-time, reverse transcription PCR. All concentrations of glucose (from 0.1 to 1%) were able to down-regulate genes from the LEE operon. A slight down-regulation of genes implicated in Shiga toxin expression was also  observed but was significant for low doses of glucose (0.1 to 0.5%) only. A slight but significant increase in luxS expression was observed with 1% glucose. This confirms that in addition to quorum sensing, the presence or absence of nutrients such as glucose has an impact on the down-  or upregulation of LEE-encoded virulence genes by the bacterium. The influence of glucose on the virulence of E. coli O157:H7 has received little attention, and these results suggest that glucose can have an important effect on the virulence of E. coli O157:H7.
authors.affiliation: Department of Food Science, University of Guelph and Canadian Research Institute for Food Safety, Guelph, Ontario, Canada N1G 2W1.
authors.forename: V
authors.initials: V
authors.lastname: Delcenserie
authors.forename: G
authors.initials: G
authors.lastname: LaPointe
authors.forename: T
authors.initials: T
authors.lastname: Charaslertrangsi
authors.forename: A
authors.initials: A
authors.lastname: Rabalski
authors.forename: M W
authors.initials: MW
authors.lastname: Griffiths
mesh_terms: D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology*; D006463:Hemolytic-Uremic Syndrome / Q000517:prevention & control; D006801:Humans; D053038:Quorum Sensing; D022621:Shiga Toxin / Q000378:metabolism*; D014774:Virulence / Q000187:drug effects* / Q000235:genetics*
chemical_list: D022621:Shiga Toxin; D005947:Glucose