Genetic Investigation of Beta-Lactam Associated Antibiotic Resistance Among Escherichia Coli Strains Isolated from Water Sources

Reza Ranjbar1, Mehrdad Sami2, *
1 Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
2 Department of Clinical Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran

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© 2017 Ranjbar and Sami.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Clinical Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran; Tel: 0098-9128902920; E-mail:



Antimicrobial resistance is an important factor threatening human health. It is widely accepted that antibiotic resistant bacteria such as Escherichia coli (E. coli) released from humans and animals into the water sources, can introduce their resistance genes into the natural bacterial community.


The aim of this study was to investigate the prevalence of blaTEM, blaCTX, blaSHV, blaOXA and blaVEB associated-antibiotic resistance among E. coli bacteria isolated from different water resources in Iran.


The study contained all E. coli strains segregated from different surface water sources. The Kirby-Bauer method and combined discs method was determined in this study for testing antimicrobial susceptibility and strains that produced Extended-Spectrum Beta Lactamases (ESBL), respectively. DNA extraction kit was applied for genomic and plasmid DNA derivation. Finally the frequency of resistant genes including blaTEM, blaCTX, blaSHV, blaOXA and blaVEB in ESBL producing isolates were studied by PCR.


One hundred E. coli strains were isolated and entered in the study. The highest antibiotic resistance was observed on clindamycin (96%). Moreover, 38.5% isolates were ESBL producers. The frequency of different ESBLs genes were 37%, 27%, 27%, and 25% for blaTEM, blaCTX, blaSHV, and blaOXA, respectively. The blaVEB wasn’t found in any isolates.


The study revealed a high prevalence of CTX-M, TEM, SHV and OXA genes among E. coli strains in surface water resources. In conclusion, these results raised a concern regarding the presence and distribution of these threatening factors in surface water sources and its subsequent outcomes.

Keywords: Antibiotic, Bacterial resistance, Escherichia coli, ESBL, PCR, Water sources.