en Environmental Health, Sciences, and Engineering Environmental Health, Sciences, and Engineering پژوهشي Original Article <div style="text-align: justify;"><span style="line-height:1;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><b><span style="color:black">Background:</span></b><span style="color:black"> The increasing prevalence of drug-resistant pathogens has drawn researchers&#39; attention to studies on the antimicrobial activity of various substances. This study investigates the antimicrobial effects of the <i><span style="background:white">Agrimonia eupatoria</span></i> and <i><span style="background:white">Nepeta Crispa</span></i> extracts, which are used as herbal medicines.</span><br> <b><span style="color:black">Methods:</span></b><span style="color:black"> The study investigated the effects of extract concentrations of 10, 20, and 40 mg/mL on three distinct bacterial strains, encompassing both types of Gram-positive and Gram-negative bacteria, including <em>Escherichia coli</em>,<i> <em>Shigella</em></i>, and <em>Clostridium perfringens</em>. The evaluation employed the well diffusion method, supplemented by the determination of the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC).&nbsp; </span><br> <b><span style="color:black">Results:</span></b><span style="color:black"> The results showed that the <i><span style="background:white">Nepeta Crispa</span></i> extract exhibited no antimicrobial effects at various concentrations, whereas the <i><span style="background:white">Agrimonia eupatoria</span></i> extract was effective against all three types of bacteria, with the diameter of the inhibition zones increasing with higher concentrations. At a concentration of 40 mg/mL, the diameter of inhibition against the three types of bacteria was approximately 8 mm. The Minimum Inhibitory Concentration for<i> <em>Escherichia coli</em></i> and <em>Shigella</em><i> </i>was 2.5 mg/mL, and for <em>Clostridium perfringens</em>, it was 1.25 mg/mL. The Minimum Bactericidal Concentration for <em>Escherichia coli</em>,<i> <em>Shigella</em></i>, and <em>Clostridium perfringens</em> was found to be 2.5 mg/mL, 5 mg/mL, and 2.5 mg/mL, respectively.</span><br> <b><span style="color:black">Conclusion: </span></b><span style="color:black">The extracts of some plants, such as </span><i><span style="background:white"><span style="color:black">Agrimonia eupatoria</span></span></i><span style="color:black"> have antibacterial properties, but their usage of them needs more investigation.</span></span></span></span></div> Agrimonia eupatoria, Nepeta crispa, Extract, Bactericidal effects, 219 224 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-39-7&slc_lang=en&sid=1 Zohre Farahmandkia zfarahmand@zums.ac.ir 100319475328460015940 100319475328460015940 No Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Somayeh Zolghadr zolghadr20.s@yahoo.com 100319475328460015941 0009-0003-5058-8295 No Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Sara Fathi sarafathizanjan@yahoo.com 100319475328460015942 100319475328460015942 No Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran. Mohammad Reza Mehrasbi zmehr@zums.ac.ir 100319475328460015943 100319475328460015943 Yes Department of Environmental Health, School of Public Health, Zanjan University of Medical Sciences, Zanjan, Iran.