Inhibition of Swarming and Virulence Factor Expression in Proteus Mirabilis by Resveratrol

Reservatol is a phytoalexin compound with anti-inflammatory and antioxidant activities. The effect of this compound on swarming and virulence factor expression of Proteus mirabilis, an important pathogen infecting urinary tract, was determined on swarming agar plates with and without the compound. Bacteria harvested at different times were assayed for cell length and the production of flagella, haemolysin and urease. We found that resveratrol dose-dependently inhibited P. mirabilis swarming and virulence factor expression. Resveratrol significantly inhibited swarming at 15 g/ml, and completely inhibited swarming at 60 g/ml. Resveratrol inhibition of swarming and virulence factor expression was mediated through RsbA, a His-containing phosphotransmitter of the bacterial two-component signaling system possibly involved in quorum sensing. Complementation of an rsbA-defective mutant with the rsbA gene restored its responsiveness to resveratol. The compound also inhibited the ability of P. mirabilis to invade human urothelial cells . These findings suggest that resveratol has potential to be developed as an antimicrobial agent against P. mirabilis infection