Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 49 12 2020 11 29 2409 2417 Omid FARAHANI Department of Microbiology, Islamic Azad University, Varamin-Pishva Branch, Varamin, Iran Reza RANJBAR Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran Sahar HONARMAND JAHROMY Department of Microbiology, Islamic Azad University, Varamin-Pishva Branch, Varamin, Iran Bahareh ARABZADEH Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran 2018 09 28 2019 03 17 Background: Escherichia coli is one of the most frequent causes of many common bacterial infections. As a potential reservoir, hospital wastewater is considered for the dissemination of bacterial pathogens such as E. coli. Therefore, research on hospital waste’s bacteria by low-cost, rapid and easy molecular typing methods such as multilocus variable-number tandem-repeat analysis (MLVA) can be helpful for the study of epidemics. Methods: E. coli strains were isolated from hospital wastewater sources in Tehran, Iran, over a 24-month sampling period (Jun 2014- Jun 2016) and identified by standard bacteriological methods. The diversity of repeated sequences of seven variable-number tandem-repeat (VNTR) loci was studied by MLVA method base on polymerase chain reaction (PCR). Results: Overall, 80 E. coli isolates were discriminated into 51 different genotypes. Analysis of the MLVA profiles using a minimum spanning tree (MST) algorithm showed two clonal complexes with 71 isolates and only nine isolates were stayed out of clonal complexes in the form of a singleton. High genotypic diversity was seen among E. coli strains isolated from hospital wastewaters; however, a large number of isolates showed a close genetic relationship. Conclusion: MLVA showed to be a rapid, inexpensive and useful tool for the analysis of the phylogenetic relationships between E. coli strains under the study. https://ijph.tums.ac.ir/index.php/ijph/article/view/14831 https://ijph.tums.ac.ir/index.php/ijph/article/download/14831/7078