جمیله نوروزی - Dept. of Microbology, Islamic Azad University, North Tehran Branch, Tehran, Iran
عباس اخوان سپهی - Dept. of Microbology, Islamic Azad University, North Tehran Branch, Tehran, Iran
نگار بزاززاده - Islamic Azad University, North Tehran Branch, Tehran, Iran

Background and Objective Widespread use of co-trimoxazole in urinary tract infection treatments and its incorrect use has led to the emergence of co-trimoxazole resistant E. coli strains. The aim of this study was to evaluate sul۲ gene among E.coli isolates of patients admitted to the clinical centers of Khoy city. Materials and Methods: Three hundred urine samples were collected from clinical centers of Khoy city. Among them, ۱۰۰ E.coli isolates were confirmed by standard biochemical tests. Furthermore, the antibiotic susceptibility tests to ۱۰ antibiotics were performed by the-disk-agar diffusion (DAD) method. Also, MIC and MBC were evaluated for co-trimoxazole by microdilution broth method. Finally, PCR was done in order to find sul۲ gene in resistant isolates. Results: Of ۱۰۰ isolates, ۷۱(۷۱%) were resistant to co-trimoxazole out of which ۵۷(۸۰%) had sul۲ gene. This gene was recognized in sulfonamides-resistant isolates which did not create any zone of inhibition. Also, the isolates with sul۲ gene were found to be simultaneously resistant to ampicillin, nalidixic acid and ciprofloxacin. In co-trimoxazole-resistant isolates, MIC and MBC for Co-trimoxazole were calculated ۱۶ and ۳۲μg/ml. Conclusion: This study was the first of its kind in Iran with the main objective of manifesting the presence of sul۲ gene in E.coli. The results of the present study indicate that antibiotic-resistance percentage in Khoy city reaches to ۷۱%. In such a situation, it is inevitable to see resistance to all common antibiotics currently prescribed to patients at clinical centers which will, in turn, result in treatment failures.

Keywords: Escherichia coli, Sulfonamides, sul۲ gene, Antibiotic resistance, disk-diffusion method, MIC