Evaluation of Antimicrobial Activity and Anti-Quorum Sensing of Rosmarinus Methanol Extract on Pseudomonas aeruginosa

Background: The increasing infections caused by resistant P. aeruginosa strains originate from hospitals. Therefore, many efforts are being made to find new herbal compounds as suitable substitutes for antibiotics. Objectives: The present study aimed to evaluate the antibacterial and anti-quorum activity of Rosmarinus methanol extract on P. aeruginosa. Methods: This experimental study was performed on standard and clinical strains of P. aeruginosa. The methanolic extract of Rosmarinus was prepared by the Soxhlet method, and the antimicrobial activity of the extract was evaluated by diffusion method in wells and microdilution. We examined the effect of this extract on the antibiofilm activity, protease, and pyocyanin production of P. aeruginosa in order to investigate the anti-quorum sensing activity of methanolic extract of Rosmarinus. Via SPSS 17, we managed to conduct the statistical analysis. Results: The mean diameter of growth inhibition zone obtained from methanolic extract of rosemary at a concentration of 500 mg/ml on Pseudomonas aeruginosa was 18.5 mm, and the minimum inhibitory concentration of methanolic extract of rosemary was 125 mg / ml for bacteria. Extract at concentrations higher than 62.5 mg /ml prevented biofilm formation, protease, and the pyocyanin production of P. aeruginosa. Conclusions: The results of the present study can be a valuable report on their useful role in infection control because the methanol extracts of Rosmarinus had suitable antibacterial and anti-quorum sensing activity. It is suggested that more studies be conducted on the identification of antimicrobials as a suitable alternative for antibiotics in the treatment of diseases.