Effect of exposure to hydrogen peroxide on the virulence of Escherichia coli.

ABSTRACT

PURPOSE: 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.