en باکتری شناسی Bactriology پژوهشي Research <div style="text-align: justify;"><strong>Background and Aims:</strong> Shigellosis is an acute gastroenteritis and Invasion plasmid antigen C (IpaC) is the first effector protein for Shigella invasion of intestinal cells. Among lactic acid bacteria, <em>Bifidobacterium lactis </em><em>(B.&nbsp;lactis)</em> has received increasing attention for protection of a potential host against gastrointestinal infections. The aim of this study was to investigate the inhibitory activity of <em>B.&nbsp;lactis</em> against <em>Shigella dysenteriae (S.&nbsp;dysenteriae)</em> harboring <em>IpaC</em> gene strains from clinical specimens.<br> <strong>Materials and Methods:</strong> Sixty stool samples of patients with bloody diarrhea were collected from three teaching hospitals in Tehran and subjected to further analysis for the identification of Shigella colonies by biochemical tests. DNA was assessed for <em>IpaC</em> gene by polymeraese chain reaction (PCR). Furthermore, IpaC gene expression analysis by real-time PCR was carried out to investigate whether probiotic <em>B.&nbsp;lactis</em> can inhibit the invasion phenotype of S. dysenteriae induced by IpaC.<br> <strong>Results:</strong> Analysis of gene expression in <em>S.&nbsp;dysenteriae</em> harboring <em>IpaC </em>gene strains showed the expression of <em>IpaC</em> gene in treated <em>S. dysentery</em> with <em>B.&nbsp;lactis</em> being much lower than that of non-treated group (p<0.000). The results revealed that <em>B.&nbsp;lactis</em> at the concentration of 500 &mu;g/ml bears strong inhibitory activity on the growth of <em>S.&nbsp;dysenteriae</em> by decreasing IpaC expression.<br> <strong>Conclusions:</strong> Our results revealed the positive role of <em>B.&nbsp;lactis</em> in reducing the expression of the <em>ipaC</em> gene and inhibition of epithelial cell invasion by <em>S.&nbsp;dysenteriae</em>. Therefore, probiotics can be used as a complementary biotherapeutic agent in severe Shigella infection.</div> Bifidobacterium lactis, Diarrhea, IpaC, Real time PCR, Shigella dysenteriae 251 258 http://ijml.ssu.ac.ir/browse.php?a_code=A-10-347-1&slc_lang=en&sid=1 Maryamsadat Mirfarsi مریم سادات میرفارسی parmismirfarsi@yahoo.com 0000-0001-5644-3255 No Department of Microbiology, Faculty of Biosciences, Islamic Azad University, Tehran North Branch, Tehran, Iran. گروه میکروب شناسی، دانشکده علوم زیستی، دانشگاه آزاد اسلامی، واحد شمال تهران، تهران Sedighe Mehrabian صدیقه مهرابیان S_Mehrabian@iau-tnb.ac.ir 0000-0002-2077-4236 Yes Department of Microbiology, Faculty of Biosciences, Islamic Azad University, Tehran North Branch, Tehran, Iran. گروه میکروب شناسی، دانشکده علوم زیستی، دانشگاه آزاد اسلامی، واحد شمال تهران، تهران Elham Siasi Torbati الهام سیاسی تربتی parmismirfarsi@yahoo.com 0000-0003-2204-0508 No Department of Microbiology, Faculty of Biosciences, Islamic Azad University, Tehran North Branch, Tehran, Iran. گروه میکروب شناسی، دانشکده علوم زیستی، دانشگاه آزاد اسلامی، واحد شمال تهران، تهران