Introduction: Escherichia coli are the most common agent of urinary tract infection. One of mechanisms of resistance to the beta-lactam antibiotics beta lactamase is enzyme production. Including beta lactamase٫as beta-lactamase producing of genes of the TEM, PER and VEB in these bacteria can be named. Purpose of present study evaluation frequency of foresaid gens extended spectrum beta lactamase producing of Escherichia coli strains isolated from urinary tract infections was in city Ilam.

Materials & methods: A total of 100 strains of E.coli were isolated from samples urinary tract and were identified using biochemical tests. Then antibiotic susceptibility was determined by disk diffusion method. Finally testing combined disk detects ESBL producing strains and MIC of strains to antibiotic CAZ and CTX by Micro broth dilution method. PCR with specific primers was used for determining the presence of blaPER, blaVEB and blaTEM genes.

Findings: Combined disk test showed 40 strains (40%) to be ESBL producing. Of the 40 ESBL producing strains, MIC for ceftazidime in the dilutions 16, 18 samples, 32, 9 samples 64, 16 samples, 128, 1 sample, 256, 2 samples were reported. MIC for cefotaxime in the dilutions 16٫13samples, 32٫9samples, 64, 5 samples, 128, 8 samples, 256, 4 samples were determined. Of the 40strains ESBL the frequency of TEM was 52.5%; however, blaPER and blaVEB genes were not detected among ESBL producing isolates.

Discussion & Conclusions: Frequency of Escherichia coli producing ESBL was 40% in city of Ilam and TEM gene in ESBL- producing E.coli isolated is the most common gene in Ilam City.