Antibacterial and antibiofilm properties of Acroptilon repens (L.) Dc extract and its effect on exotoxin A gene expression of Pseudomonas aeruginosa

The goal of this study was to investigate the effect of Acroptilon repens ethanolic extract, chloroform, ethylacetate, and water fractions and effect of these on the expression of gene encoding exotoxin A virulence factor in Pseudomonas aeruginosa. Antibacterial activity of the extract and fractions of A. repens against P. aeruginosa was determined by the well diffusion and disk diffusion methods. In addition, broth microdilution susceptibility testing was carried out to determine the minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC). The effect of extract and fractions on biofilm formation was evaluated by a microtiter plate assay. Real time PCR technique was used to determine the expression of exotoxin A gene. The results showed that the extract and fractions of A. repens inhibited the growth of P. aeruginosa significantly (p < 0.0001). Compared with chloroform and ethyl acetate fractions, the ethanolic extract and water fraction showed stronger inhibition zones (p < 0.05), and the water fraction has the most antibiofilm effect on P. aeruginosa strains (p < 0.0001). The expression level of exoA gene decreased in the presence of extract of A. repens and its fractions (P < 0/0001). The results obtained from Ct were analyzed by SPSS software and one way ANOVA test. There was a significant difference between Ct Values and Log10 Template molecules (P < 0.0001). Based on the results obtained in this study, the ethanolic extract and fractions of A. repens can be used as a candidate for a new source of medicine for nosocomial infections caused by drug-resistant P. aeruginosa strains.