en بهداشت Health تحقیقی Original article <div style="text-align: justify;"><strong><em>BBackground and Objective</em></strong><strong>:</strong> <em>Pseudomonas aeruginosa</em> is an important case of nosocomial infections and a major health problem. The increased emergence of resistance to antibiotics and disinfectants among these bacteria, necessitates the production of new antimicrobials with wider activity and low toxicity. This study was carried out to evaluate inhibitory effects of chlorhexidine gluconate and extract of <em>Peganum harmala </em>on multi-drug resistant (MDR) <em>P. aeruginosa</em>.<br> <strong><em>Material and Methods:</em></strong> 39 <em>P. aeruginosa</em> strains were isolated from 114 environmental samples. After identifying MDR strains, minimal inhibitory concentration (MIC) of chlorhexidine gluconate (20%) and <em>P. harmala</em> extract against the isolates was determined by broth microdilution method.&nbsp;<br> <strong><em>Results:</em></strong> Overall, 27 (69.2%) <em>P. aeruginosa</em> isolates resistant to quinolones, aminoglycoside, cephems and carbapenems were reported as MDR strains. The MIC of chlorhexidine gluconate was &ge; 1000&mu;g/ml, which was 4-fold higher than the MIC of <em>P. harmala </em>extract (MIC<span style="color:#000000;">=5</span>00&mu;g/ml). MIC of chlorhexidine gluconate and <em>P. harmala </em>extract against <em>P. aeruginosa</em> isolates differed significantly (<em>P</em>=0.01).<br> <strong><em>Conclusion:</em></strong> Compared to chlorhexidine gluconate, <em>P. harmala </em>extract has a higher antibacterial effect on MDR <em>P. aeruginosa</em> isolates from environment. Further research is required to verify the efficacy of this plant extract for disinfection of equipment in clinics and local kitchens.</div> Bacterial contamination,Pseudomonas aeruginosa,Peganum,Chlorhexidine gluconate, 42 48 http://goums.ac.ir/jorjanijournal/browse.php?a_code=A-10-541-3&slc_lang=en&sid=1 Elham Hashempour elham.hp95@gmail.com 10031947532846007089 0000000271784100 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Leila Fozouni L.fozouni@gorganiau.ac.ir 10031947532846007090 0000000222480354 Yes Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Ania Ahani Azari ania_783@yahoo.com 10031947532846007091 0000000170256739 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran