Quorum sensing-regulated functions of are reduced by eugenol.

BACKGROUND AND OBJECTIVES

has emerged as a nosocomial pathogen responsible for human infections, where antibiotic resistance further complicates the treatments. In , biofilm formation and virulence factor production are controlled via quorum sensing (QS) system. QS is a signaling system that enables gene regulation to control diverse physiological functions in bacteria. Essential oils have shown to be potential in diminishing the pathogenicity and virulence of drug-resistant bacteria. This study was performed to determine whether eugenol would affect QS system, biofilm formation and virulence factor production of

MATERIALS AND METHODS

Biofilm formation, extracellular virulence factor production (hemolysin and protease), swarming motility and pigment formation of ATCC 13880 and Sm2 were assessed after eugenol exposure at 1.25 and 2.5 µg/ml concentrations. The expression of genes involved in motility , attachment , biofilm formation , and QS regulatory were also evaluated.

RESULTS

Eugenol treatment at 1.25 and 2.5 µg/ml concentrations caused a significant reduction in biofilm formation. The pigment, hemolysin and protease production of two studied strains, also reduced significantly by eugenol treatments (p<0.05). The and genes were down-regulated after eugenol treatment. The gene expression was also reduced significantly by eugenol in both strains (<0.05).

CONCLUSION

Eugenol inhibited quorum sensing-regulated functions of two studied strains.