محمد کاظم شریفی یزدی - Dept. of Laboratory, Faculty Paramedical Sciences, Tehran University of Medical Sciences. Tehran, Iran
محمد آذرسا - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
محمدحسن شیرازی - Antimicrobial Resistant Research Center, Tehran University of Medical Sciences, Tehran Iran
عبدالعزیز رستگاری لاری - Dept. of Medical Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
پرویز اولیا - Dept. of Medical Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran .
جلیل فلاح مهر آبادی - MARS Bioinformatics Institute, Tehran, Iran.
هدروشا ملا آقا میرزایی - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
آیلار صباغی - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
فرناز شامکانی - Dept. of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, International Units(ARAS), Iran
گلناز مبصری - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
روناک بختیاری - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
محمدمهدی سلطان دلال - Devision of Microbiology, Dept. of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.

Background and Objective: The production of Extended Spectrum Beta Lactamases (ESBLs) by Escherichia coli is the main cause of resistance to Cephalosporins.  In the past decade, CTX-M enzymes have become the most prevalent ESBLs in Europe, Canada, and Asia.  In this study, the frequency of ESBL-producing E.coli and molecular detection of the CTX-M-I group was investigated. Materials and Methods: A total of ۴۰۰ urine samples were collected from both hospitalized and out-patients in Khoy’s hospitals between November ۲۰۰۹ and April ۲۰۱۰.  Out of these samples, ۱۸۸ were identified as  E.coli  by standard biochemical tests. The antibiotic Susceptibility tests to ۱۰ antibiotics were performed by the-disk-agar diffusion (DAD) method. ESBL production was screened by phenotypic test that including disk diffusion agar and combined disk as recommended by the Clinical and Laboratory Standards Institute (CLSI). Screened isolates were investigated by PCR assay for detection of CTX-M-I group genes. Results: The results show that out of ۱۸۸ E.coli isolates identified, ۵۶ (۲۹.۸%) were producing ESBls by phenotypic test. All isolates were sensitive to imipenem. Overall, ۴۹ (۸۷.۵%) isolates were confirmed as CTX-M-I producer by PCR. Conclusion: The results of this study showed that about ۳۰% of the identified E.coli were producing ESBl. Therefore, we recommend to use molecular methods in such researches.

E.coli, Extended Spectrum Beta Lactamase, CTX-M-I, Antimicrobial resistance