Uncorrected Proof Gene Cell Tissue. In Press(In Press):e97554. Published online 2019 December 23. doi: 10.5812/gct.97554. Research Article Investigation of Antimicrobial Resistance Pattern Among Escherichia coli Strains Isolated from Patients Referred to Amir Al-Momenin Hospital, Gerash, Iran Aliyar Piruozi 1 , Hossein Forouzandeh 1, * , Abbas Farahani 2 , Jebreil Shamseddin 2 , Hamideh Mohseni 3 , Ahmad Abdollahi 1 , Elham Rezaee 1 , Zahra Forouzandeh 4 , Parisa Mohseni 5 and Fatemeh Fariyabi 6 1 Cellular and Molecular Research Center, Gerash University of Medical Sciences, Gerash, Iran 2 Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran 3 Islamic Azad University of Larestan, Larestan, Iran 4 Nursing School, Jahrom University of Medical Sciences, Jahrom, Iran 5 Shahid Beheshti University of Medical Sciences, Tehran, Iran 6 Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Shiraz, Iran * Corresponding author: Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Shiraz, Iran. Email: hosainforuozandeh@yahoo.com Received 2019 August 28; Revised 2019 November 30; Accepted 2019 December 02. Abstract Background: Antibiotic resistance is now considered as a global problem. Due to the increasing use of antibiotics, and subsequent increase in antibiotic resistance, treatment of bacterial infections has faced many difficulties. Objectives: This study aimed to investigate the pattern of antibiotic resistance in Escherichia coli (E. coli) isolated from patients referred to the hospital during the years 2016 - 2018. Methods: In this cross-sectional study, 2250 samples were taken from outpatient and hospitalized patients (inpatients) during three years (2016 - 2018). After collection, the specimens were cultured in blood agar and EMB media. One thousand six hundred and forty- two positive samples were obtained that from these, a number of 1067 specimens were recognized as E. coli. Antibiotic susceptibility was determined using a disk diffusion method on Mueller Hinton agar media for eight antibiotics. The result was evaluated based on the Clinical Laboratory Standards Institute (CLSI). Results: In this study, 1642 positive samples were diagnosed that the largest isolated strains were associated with E. coli (65%). About 241 samples belonged to men (22.6%) and 826 samples were isolated from women (77.4%). Based on the findings, most cases of resis- tance were related to co-trimoxazole with 52.6% and the highest sensitivity was related to nitrofurantoin with 81%. Conclusions: The results of this study indicated that the pattern of antimicrobial resistance is increasing and urinary tract infection (UTI) caused by E. coli isolates with a high rate of resistance still remains an important healthcare problem. Therefore, continuous evaluation of the pattern of resistance in different areas is necessary for promotion of antibacterial management. Keywords: Escherichia coli, Antimicrobial Resistance, Outpatients, Inpatients 1. Background Since recognizing bacteria, humans have been always looking for effective medications against infections caused by these microorganisms. In addition, bacteria have achieved effective mechanisms to eliminate antibiotic ef- fects. Following the development of antibiotic-resistant organisms, nowadays, we have had several reports on widespread outbreaks in different wards of hospitals (1, 2). Development of drug resistance has been considered as a common situation. The treatment of this type of illness has caused many problems (3, 4). E. coli is ubiquitous and found in water, soil, plants and makes the normal flora of human and animal intestines. This bacterium is the most important common micro- bial agent of urinary tract infections. It is the cause of many hospital opportunistic infections such as sepsis, gas- tric wounds, urethritis, and neonatal meningitis (5-7). This organism is resistant to beta-lactam antibiotics due to the acquisition of plasmids that encode broad-spectrum beta- lactamases. Based on these facts, the treatment of E. coli in- fection has been problematic (8). Copyright © 2019, Gene, Cell and Tissue. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.