title: Effect of exposure to hydrogen peroxide on the virulence of Escherichia coli.
abstract: OBJECTIVE
  To eliminate pathogenic bacteria, the host presents conditions that are stressful for bacteria. Oxidative stress arises when the concentration of pro-oxidants like hydrogen peroxide (H2O2 ) and superoxide anion increases to a level over the basal defence capacity of the cell. In the present study, we studied the effect of oxidative stress on the production of certain virulence factors by Escherichia coli .
  
  
  METHODS
  E. coli was exposed to oxidative stress by growing in the presence of different concentrations of H2O2 . The effect of oxidative stress on the expression of surface hydrophobicity, adherence, haemolysin production, serum resistance and phagocytosis was studied.
  
  
  RESULTS
  Oxidative stress caused a significant decrease in the expression of all the virulence factors of E. coli .
  
  
  CONCLUSIONS
  Synthesis of virulence factors can be significantly altered by oxidative stress and such changes may affect the pathogenicity of E. coli.
authors.affiliation: Department of Microbiology, Kasturba Medical College, Mangalore - 575 001, Karnataka, India.
authors.forename: A
authors.initials: A
authors.lastname: Hegde
authors.forename: G K
authors.initials: GK
authors.lastname: Bhat
authors.forename: S
authors.initials: S
authors.lastname: Mallya
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000096:biosynthesis; D006460:Hemolysin Proteins / Q000096:biosynthesis; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D057927:Hydrophobic and Hydrophilic Interactions; D010587:Phagocytosis / Q000187:drug effects; D014774:Virulence / Q000187:drug effects; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; D037521:Virulence Factors; D006861:Hydrogen Peroxide