en علوم آزمایشگاهی Laboratory Sciences Research Article Research Article <span style="font-size:12px;"><span style="font-family:Times New Roman;"><b>Background:</b> <i>Escherichia coli</i> consists of a wide range of strains with huge diversity in their genome, distributed in nature and the alimentary tracts of animals and humans. This study analyzed the phylogenetic group determination and genetic diversity of <i>E. coli</i> strains isolated from domestic animals and human clinical samples.<b><span style="font-size:8.0pt"></span></b><br> <b>Methods:</b> Twenty <i>E. coli</i> isolates from domestic animals were analyzed for phylogenetic grouping. Also, 100 clinical samples and 20 animal samples were evaluated by the enterobacterial repetitive intergenic consensus&ndash;polymerase chain reaction (ERIC-PCR) technique. The results and the similarity between the strains were determined based on the Dice similarity coefficient in the SAHN program of the NTSYS-pc software.<b><span style="font-size:8.0pt"></span></b><br> <b>Results:</b> The frequency of phylogroups among animal samples were A = 5%, B1 = 65%, B2 = 20%, and D = 10%. Based on the ERIC-PCR results, the clinical strains were allocated into 19 clusters. Most strains were in the E7 cluster. Fifty percent of the E. coli isolated from animal specimens belonged to the E4 group, and the lowest number of strains was in the E3 and E5 (1 strain) groups.<br> <b>Conclusion</b>: The results confirmed the efficiency and usefulness of the ERIC-PCR tool for the identification and classification of bacteria. Also, we demonstrated the most phylogroup among animal samples.</span></span><br> &nbsp; Escherichia coli,Phylogeny,Animals,Humans 22 25 http://mlj.goums.ac.ir/browse.php?a_code=A-10-1424-1&slc_lang=en&sid=1 aliehsan karshenas aekarshenas52@gmail.com 100319475328460027447 100319475328460027447 No Department of Pathobiology, science and research branch, Islamic Azad University, Tehran, Iran ramak yahya raiat Ramak_Yahyaraeyat2023@yahoo.com 100319475328460027448 100319475328460027448 No Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran taghi zahraiee salehi Taghi_Zahraei_Salehi@yahoo.com 100319475328460027449 100319475328460027449 No Department of Microbiology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran babak asghari babasghari2024@yahoo.com 100319475328460027450 100319475328460027450 No Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran maryam adabi maryam_adabi@yahoo.com 100319475328460027451 100319475328460027451 Yes Infectious Ophthalmologic Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran