Antimicrobial Activity of Some Medicinal Plant Extracts against Multidrug Resistant Bacteria

Background: Nowadays, it is necessary to discover new and efficient antifungal or antimicrobial drugs because of increasing drug resistance organisms. Using medicinal plants for natural treatment of diseases caused by bacterial origin has mainly been considered. Objectives: In this study, the impacts of antimicrobial medicinal plants extract were compared based on four bacteria in vitro. Methods: In this experimental study, disc diffusion assay and the minimum inhibitory concentration (MIC) method were used to investigate the antibacterial effects of selected plant extract elicited by two different solvent on S. aureus, E. coli, P. aeruginosa and S. enteric. Data were analyzed with a statistical software program (SPSS 16). Results: The hydro-alcoholic extract of Myrtus communis (myrtle) and water extract of Cinnamomun zeylanicum (cinnamon) were the most active extracts screened for antimicrobial activities against different four bacteria as tested organisms. The diameter of inhibition zones ranged from 23 to 28 mm. Comparison of the antibacterial effect of plant extracts and commercial drug revealed that the size of inhibition zone of penicillin against Staphylococcus aureus bacterium was larger than the plant extracts. However, myrtle extract at the minimum inhibitory concentration (MIC) of 30 mg/mL showed more powerful antibacterial activity compared to the other extracts and even penicillin. Petroselinum crispum (parsley), Nerium oleander (Oleander) and Glycyrihiza glabra (licorice) were found to have the least effect on the tested bacteria. Conclusions: In the present study, plant extracts with different compounds showed antibacterial activity (especially myrtle and cinnamon). Hence, they can be used as new source for antibacterial substances.