Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 5 1-2 2016 12 31 15 20 EN Mohammad Dadook Faculty of Biological Sciences, Islamic Azad University, Tehran North Branch, Tehran, Iran. Sedigheh Mehrabian Faculty of Biological Sciences, Islamic Azad University, Tehran North Branch, Tehran, Iran. Saeed Irian Department of Cell and Molecular Biology, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran. 2016 12 31 2016 12 31 Background: Medicinal use of plants dates long back in the history of the human beings and has recently gained a great deal of importance in treating different diseases. Due to the importance of Pseudomonas aeroginosa strains as agents responsible for common secondary infections and their resistance to antibiotics and disinfectants, the present study aimed at investigating the antimicrobial effects of the plant Cyperus rotundus on multiple drug resistant (MDR) P. aeruginosa strains.  Methods: Ethanolic extracts of Cyperus rotundus tuber were prepared by maceration. The antimicrobial effect of these extracts on P. aeruginosa isolates (ie., sensitive to antibiotics and multiple drug resistant strains), isolated from clinical and soil samples, was determined by both disk diffusion and broth microdilution methods..  Results: It was revealed that ethanolic extract concentrations of Cyperus rotundus tuber higher than 0.1 mg/ml suppresses the growth of all antibiotic sensitive and resistant P. aeruginosa strains which were used in this study.  Conclusion: It is concluded that Cyperus rotundus possesses antimicrobial properties and thus can be used in treating multidrug resistant P. aeruginosa-induced wounds and infections. https://jmb.tums.ac.ir/index.php/jmb/article/view/226 https://jmb.tums.ac.ir/index.php/jmb/article/download/226/160