Plants have been used for their medicinal properties for thousands of years. From ancient times, different scientists and physicians had used various types of herbs to treat diseases and many books and treatises had been written to describe different effects of different plants on different maladies. Emerging the drug resistant pathogens in recent decades prompted the scientists to evaluate the effects of the medicinal plants against pathogens. Plantago major is one these herbs which its values has been praised since time immemorial. P. major has been used to treat different kinds of maladies including infectious diseases. Thus, we conducted this survey to evaluate the antimicrobial activities of this herb against three common pathogens: Staphylococcus aureus, Escherichia coli and Listeria monocytogenes. To achieve this purpose, the activity of the P. major both aqueous and alcoholic extract against mentioned pathogens was scrutinized by disc diffusion method and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the seed extracts were determined as well. Our results showed that the MIC of the aqueous extract was between 0.022 mg/mL and 0.045 mg/mL for S. aureus and between 0.09 mg/mL and 0.181 mg/mLfor both E. coli and L. monocytogenes; however, the aqueous extract did not show any bactericidal activity and no inhibitory zone was detected by disc diffusion method. Strains which were used in this inquiry were completely resistant to the alcoholic extract and thus its MIC and MBC remained undetermined and no inhibitory zone was detected.

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