الفهرس 
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Abstract
One of the important resistant mechanisms in Gram-negative bacteria against beta-lactam antibiotics is the production of beta-lactamase enzyme Li Q., et al. (2001). Evolution of beta lactamase enzyme was due to the use of new broad-spectrum antibiotics such as Cephalosporins which are used in the treatment of bacterial infections Schwaber and Carmeli. (2007)Extended-spectrum Beta-lactamases (ESBLs) recognized in 1980s, in Klebsiella species and later in Escherichia coli and other Gram-negative bacilli are currently spreading rapidly amongst other members of enter-obacteriaceae, largely due to genes located on plasmids that can distribute across species barriers Falagas and Karageorgopoulos. (2009).Infections with ESBL producing bacteria are associated with nearly twice themortality compared to non-ESBL producers Ruppé.,(2010). Carriage of resistance by commensal Enterobacteriaceaestrains in the gut may serve as a reservoir of resistance genes that may subsequently be acquired by strains that cause clinically significant infectionKariuki and Hart. (2001). More than 200 types of ESBLs have been found worldwide, which comprised of mainly 157 TEM, 101 SHV and 65 CTX-M variants Liu. et al.(2008).The ESBL producing diarrhoeagenicE. coli can be detected either by phenotypic or genotypic methods. Phenotypic methods are not always consistent Garrec, et al. (2011).Hence genotypic methods have proven to be a more useful option for detection. More-over, carriage of ESBL producing E.coli isolated from urine samples in pediatric population can create a larger threat to the community through widespread transmission of these strains. Thus, the aim of our study was to detect the burden of ESBL producing E.coli in urine sample of children by phenotypic and genotypic methods.A total of 600 urine samples were examined for presence of E. coli and those producing ESBL enzymes. Urine samples were cultured for aerobic bacteria and antimicrobial susceptibility testing carried out by using Kirby-Baur agar diffusion method. E. coli were tested for ESBLs on Mueller-Hinton agar by double disk. E. coli was the most common bacteria isolated from urine 117 (32.5%). E. coli isolated from urine are tested for ESBL production and it was found that 60 (51.3%) E.coli were totally susceptible to imipenem(100%) and variable resistant to another antibiotics. The ESBLs producing E. coli are highly resist to different types of antibiotics, especially third generationcephalosporins.The production of extended-spectrum- β lactamases (ESBLs) is an important mechanism for resistance to the third-generation cephalosporins. ESBLs represent a major group of lactamases enzymes that mostly produced by Gram negative bacteria, so the detection of these enzymes are very important for optimal patients care. The present study was done to detect extended spectrum beta lactamase producing E. coli among urinary tract infected patients.Finally detection of beta lactamases and evaluation of genetic clinical isolates would beuseful in epidemiological studies and to provide biochemical and molecular basis for bacteriological resistance.