Nader Kazemi - Nanobiotechnology Research Center, Zanjan Branch, Islamic Azad University, Zanjan, Iran
Mahdi Arfaei - Nanobiotechnology Research Center, Zanjan Branch, Islamic Azad University, Zanjan, Iran

Background and Aim : Infectious diseases are one of the most common diseases around the worldwhich impose enormous financial burden on society. Staphylococcus aureus is an important causesof nosocomial infections and multidrug resistance. Although synthetic antibiotics have been ableto play an important role in treatment of infectious diseases in past decades, however problemsrelated to microbial resistance of antibiotics have caused that the medical plants to be consideredas an alternative.Methods : In this study, aqueous and ethanolic extracts were prepared from dried leaves of theTrachyspermum copticum and Melissa Officinalis, then anti-bacterial activities of the extracts forStaphylococcus aureus were experimented, first by the method of well diffusion in agar, and laterthe amount of the MIC and MBC of the extracts were measured by broth dilution method. Inanimal model study, first ۵×۱۰۵ CFU/ml of bacteria was intraperitoneally injected and after ۲۴hours, ۰.۵ml (as MBC concentration of each the extracts) of extracts, to female BALB/c mice wasintrapertioneally injected. Then, the counting of bacterial clonies in spleen were determined withcultivation on Mueller Hinton agar after ۷ days as the standard protocol.Results : The experiment results concerning the determination of growth inhibition diameter inagar showed that the maximum of growth inhibition diameter is related to the ethanolic extract ofTrachyspermum copticum (۲۰ mm), and the minimum of growth inhibition diameter is related toethanolic extract of Melissa Officinalis (۱۰ mm) at the highest concentration (۴۰۰ mg/ml). Inconditions of in vivo, after ۴۸ hours spleen supernatant cultivation, the average number of bacteriafor ethanolic extracts of the Trachyspermum copticum and Melissa Officinalis were ۱.۸×۱۰۳CFU/ml and ۶.۶×۱۰۳ CFU/ml respectively and for aqueous extract of Trachyspermum copticumwas ۱۴.۶×۱۰۳ CFU/ml. These results showed significantly decrease in number of bacteria in allexperimental groups (p?۰.۵) compared to control group.Conclusion : In general, the results of evaluations in experimental conditions and the animalmodel showed that ethanolic and aqueous extracts of Trachyspermum copticum and ethanolicextract of Melissa Officinalis have the effective antibacterial activity against mentioned bacteriaand can be useful to treatment of nosocomial infections.

Antimicrobial, Melissa Officinalis , Staphylococcus aureus , Trachyspermumcopticum