en ميکروب شناسي Microbiology تحقيقي Original Paper <div><strong>ABSTRACT</strong><br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Background and Objectives:</strong> Probiotics are live microorganisms that function through &nbsp;various mechanisms &nbsp;and affect the alteration of the commensal microbiota against pathogens. Nowadays, &nbsp;given the problems associated with antibiotics use, probiotic strains &nbsp;offer a novel and &nbsp;appropriate &nbsp;alternative for the treatment of diseases such as diarrhea. The aim of this study was to investigate the antibacterial synergism of <em>Lactobacillus spp</em>., <em>Bifidobacterium spp</em>. and <em>Escherichia coli</em> strain Nissle 1917 (ECN) on the clinical sample of diarrheagenic <em>E.coli</em> and <em>Campylobacter jejuni. </em><br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Methods: </strong>A paper disk-diffusion technique was used to evaluate the antibacterial activity. Sterile 6 mm paper disks were saturated with probiotic suspensions made by settling probiotic medications into distilled water. Three kinds of disk were prepared. One disk was prepared for <em>Lactobacillus spp</em>. and <em>Bifidobacterium spp</em>., another for ECN, and the third was made by combined probiotics. Clinical samples of diarrheagenic <em>E.coli</em> and <em>Campylobacter jejuni</em> were cultivated on Muller Hinton agars, and disks were placed on the inoculated Muller Hinton agars. All plates were incubated under microaerophilic and appropriate conditions.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Results: </strong>The zone of inhibition (ZOI) of the bacterial growth was measured. All pathogenic microorganisms showed sensitivity to the probiotic disks. The combined disks had better effects against pathogens compared with single disks.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Conclusion: </strong>A considerable synergistic effect was observed in the results of combined probiotics; therefore, combined strains can be more efficient against intestinal pathogens in comparison with single probiotics.<br> <strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Keywords:</strong> Probiotic, <em>Lactobacillus</em>, Bifidobacterium, <em>Escherichia coli</em> Nissle, Diarrhea, <em>Campylobacter jejun.i</em>.</div> Probiotic , Lactobacillus ,Bifidobacterium , Escherichia coli Nissle 1917, diarrhea , Campylobacter jejuni 15 19 http://mlj.goums.ac.ir/browse.php?a_code=A-10-589-2&slc_lang=en&sid=1 Hamidreza Ebrahimnezhad hamidrezaebi20@gmail.com 100319475328460017392 100319475328460017392 No Student of pharmacy, Department of Pharmaceutics, Baqiyatallah University of Medical Sciences,Tehran,Iran Leila Barzegar esmaeili14@yahoo.com 100319475328460017393 100319475328460017393 No Department of Microbiology and Applied Microbiology Research Center, Systems Biology and Poisonings Institute, BaqiyatallahUniversity of Medical Sciences, Tehran, Iran Davoud Esmaeili esm114@gmail.com 100319475328460017394 100319475328460017394 Yes Applied VirologyResearch Center, BaqiyatallahUniversity of Medical Sciences, Tehran, Iran, and Department of Microbiology and Applied Microbiology Research Center, Systems Biology and Poisonings Institute, BaqiyatallahUniversity ofMedical Sciences, Tehran, Iran