Targeting Biofilm and Quorum Sensing in 𝑃𝑠𝑒𝑢𝑑𝑜𝑚𝑜𝑛𝑎𝑠 𝑎𝑒𝑟𝑢𝑔𝑖𝑛𝑜𝑠𝑎 by Quercetin, Meloxicam, and Their Potential Synergy with Colistin

Pseudomonas. Aeruginosa (P.aeruginosa) is a vital pathogenic bacterium with limited therapeutic options. In our previous research, we proved by in silico studies that quercetin and meloxicam could act as inhibitors for the auto-inducer molecules of the Quorum sensing system (QS) system LasR and rhlR in P.aerogenosa. The study aimed to validate the effect of quercetin and meloxicam on expression of lasR and rhlR genes, to investigate their effect on biofilm forming ability as an important virulent factor controlled by the (QS) system, and to examine their combination with colistin antibiotic. Strong biofilm former P. aeruginosa isolates were selected and PAO1 strain as reference strain, treated separately by sub-inhibitory of quercetin and meloxicam. Quercetin and meloxicam were found to have significant inhibitory effect biofilm formation with down regulation for the QS genes lasR and rhlR. As tested by real time PCR. In addition, colistin combinations with quercetin or meloxicam were tested by checkerboard method. This study indicated that both quercetin and meloxicam have a significant inhibitory effect on biofilm. Hence, they may be used as quorum sensing inhibitors (QSI). Furthermore, quercetin was found to have a synergetic effect with colistin.

Targeting Biofilm and Quorum Sensing in 𝑃𝑠𝑒𝑢𝑑𝑜𝑚𝑜𝑛𝑎𝑠 𝑎𝑒𝑟𝑢𝑔𝑖𝑛𝑜𝑠𝑎 by Quercetin, Meloxicam, and Their Potential Synergy with Colistin Keywords:

Anti quorum sensing , Biofilm , Pseudomonas aeruginosa , Quercetin , Meloxicam