Amir mohammad Ghasemian zeydanlo - Bsc. Of Microbiology, Department of Biology, Faculty of Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran.
Maryam Farhadmanesh - Bsc. Of Microbiology, Department of Biology, Faculty of Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran.
Ehsan Yousefi - Ph.D. Student of Microbiology, Department of Biology, Faculty of Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran.
Mahboobeh Nakhaei Moghadam - Associate Professor, Department of Biology, Faculty of Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran.

Background and Aim : Following the development of drugs, microorganisms become resistant to them through a variety of mechanisms. In recent years, the prevalence of antibiotic resistance has increased dramatically and the treatment of diseases caused by them has become more difficult. In this regard, new drugs are being developed. The aim of this study was to study the inhibitory effect of hydroalcoholic extracts of Dysphania botrys and Artemisia khorassanica on some bacteria.Methods : Artemisia khorassanica (Family: Asteraceae) and Dysphania botrys (Family: Amaranthaceae) were collected from suburbs of Quchan (Khorasan Razavi province). After extracting the hydroalcoholic extract of the mentioned plants, blank discs impregnated with ۲ mg of the extract were prepared using DMSO. Inhibitory effect of the extracts was determined by disk diffusion method based on Kirby Bauer standards. Klebsiella pneumoniae (ATCC ۷۰۰۶۰۳), Micrococcus, Staphylococcus aureus (PTCC۱۱۱) and Staphylococcus epidermidis (ATCC۱۲۲۲۸) and ۱۵ clinical isolates of K. pneumoniae were inoculated on Mueller-Hinton agar. Clinical isolates were previously identified using differential biochemical tests and confirmed with ۱۶S rRNA primer and polymerase chain reaction. Standard gentamicin disk and blank disk were placed on the plate as positive and negative controls.Results : The results showed that the highest effect of D. botrys on S. aureus (۱۸ mm) and the highest effect of A. khorassanica on K. pneumoniae (۱۲ mm). The minimum inhibition concentration (MIC) of D. botrys was ۵۰۰ ?g/ml against S. aureus.Conclusion : The results of this study showed that these two plants or their effective compounds can be a good candidate for the more effective treatment of bacterial infections.

Dysphania botrys, Artemisia khorassanica, Antimicrobial activity, Diffusion disk