en ميکروب شناسي Microbiology Research Article Research Article <strong>Background and objectives:</strong> Garlic is a medicinal plant with various health promoting properties including antimicrobial effects. In this study, we investigated in vitro antibacterial effects of garlic hydro-alcoholic extract against enterohemorrhagic <em>Escherichia coli</em> (EHEC).<br> <strong>Methods:</strong> Garlic hydro-alcoholic extract was prepared by maceration method. &nbsp;Phytochemical analysis of the extract was carried out using gas chromatography-mass spectrometry. Minimum inhibitory concentration (MIC) of the extract against EHEC was determined by micro-dilution assay. Cytotoxic effect of the garlic extract on human colon adenocarcinoma cell line (SW480) was assessed using MTT assay. Micro-dilution assay was also used to determine the MIC of the extract against EHEC when co-cultured with SW480 cells.<br> <strong>Results:</strong> The amount of organosulfur in garlic extract was 70.91% and the most common organosulfur compounds were trisulfide, di-2-propenyl (34.8%) and diallyl disulfide (14.83%). The MIC of garlic hydro-alcoholic extract on EHEC alone and when co-cultured with SW480 was 12.5 mg/ml. Concentrations of 12.5 mg/ml and 25 mg/ml of the extract significantly reduced the viability of SW480 cells compared to control and concentration of 6.25 mg/ml of garlic extract (p <0.0001).<br> <strong>Conclusion:</strong> The garlic hydro-alcoholic extract has inhibitory effects on EHEC in vitro. Therefore, it can be considered a suitable candidate for controlling infections caused by EHEC. Cell line,Plant extracts,Garlic, 25 31 http://mlj.goums.ac.ir/browse.php?a_code=A-10-826-1&slc_lang=en&sid=1 Zynab badeli zbadeli@shirazu.ac.ir 100319475328460021433 100319475328460021433 No Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Masoud Haghkhah 100319475328460021434 100319475328460021434 No Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran Ezzat Allah Ghaemi eghaemi@yahoo.com 100319475328460021435 100319475328460021435 Yes Laboratory Sciences Research Center, Golestan University of Medical Sciences, Gorgan, Iran