Faculty of Biotechnology and Food Sciences in Nitra Journal of Microbiology, Biotechnology and Food Sciences 1338-5178 vol. 5 2016 2016-04-01 2016-04-01 ANTIMICROBIAL ACTIVITY OF SOME ESSENTIAL OILS ALONE AND IN COMBINATION WITH AMIKACIN AGAINST ACINETOBACTER SP 412 415 EN Mohaddese Mahboubi Mohaddese Mahboubi Mohammad Mehdi Feizabadi Mohammad Mehdi Feizabadi Acinetobacter sp. as gram negative bacilli is one of the most problematic bacteria in hospital environments. The emergence of multi-drug resistant isolates of Acinetobacter sp. encourages the scientists to find the new antimicrobial agent with less side effects. The aim of this study was to evaluate the antibacterial activity of Cymbopogon olivieri, Heracleum persicum, Juniperus comminus, Azillia eryngioides, Dacus carrota, Ferula gummosa, Acorus calamus, Mentha pulegium, Achillea biebersteinii, and Chaerophyllum macropodum essential oils against clinical trials of Acinetobacter sp. by disc diffusion and micro broth dilution assays. The synergistic effect of these essential oils and amikacin (AMI) were determined. The higher inhibition zone diameters were for 2 µl of C. macropodum (15.3±0.48 mm). The lower MIC and MBC values were for C. olivieri (1.4 and 1.9 µl/ml) and J. comminus (1.9 and 2.6 µl/ml), followed by C. macropodum (2.01 and 3.2 µl/ml), D. carrota (2.1 and 3.8 µl/ml), A. eryngioides (2.3 and 3.1 µl/ml) essential oils and F. gummosa (2.4 and 4 µl/ml). AMI showed synergistic effect with all of the essential oils. D. carrota and A. eryngioides showed the best synergistic effect with AMI, followed by C. macropodum, A. biebersteinii, J. comminus and F. gummosa essential oils.