Background: Acute diarrhea, a leading cause of morbidity and mortality worldwide, still remains a major global health problem, especially among children in the developing countries. Diarrheagenic E. coli represent one of the most common etiological causes of diarrhea in children worldwide. Objectives: This study was conducted in order to determine the rate of Enteroaggregative E. coli (EAEC) among 50 E. coli isolates as well as its antimicrobial resistance patterns. Methods: A total of 50 Escherichia coli strains had been isolated among children under 5 years of age during 75 reported outbreaks in various provinces of Iran from October 2013 to May 2014. PCR was employed for the identification of different groups of diarrheagenic E. coli. Antimicrobial susceptibility testing was performed using disc diffusion methods. In addition, extended spectrum beta-lactamase (ESBL) production ability was checked by way of combination disc methods of CLSI. Minimum inhibitory concentration of cefotaxime, ceftriaxone, and ceftazidime in EAEC with the ability of ESBL production was determined using the micro-broth dilution method of CLSI. Results: Out of the 50 E. coli isolates, 17 were identified as Enteroaggregative E. coli (EAEC) in that they were positive for at least 1 of the 2 tested virulent genes: agg and aap. ESBL production ability was observed in 4/17 (23.5%) EAEC isolates. MIC of cefotaxime and

Background: FExtended spectrum beta-lactamases (ESBLs) are known as enzymes that are responsible for creating high level of antimicrobial resistance in gram negative microorganisms especially in Escherichia coli. Therefore, survey and identification of the genes generating these enzymes can be effective in controlling the resistance and helpful in using appropriate β-lactam drug against them. Objective: In this study we focused on evaluating the prevalence of ESBL enzyme genes, including CTX-M, SHV, and TEM β-lactamase, among E. coli isolates in foodborne disease outbreak. Materials and Methods: Four hundred stool samples from the individuals with diarrhea, nausea, vomiting, abdominal cramps, fever and headache were tested by IMVIC biochemical test for E. coli. ESBL genes were determined using antimicrobial susceptibility test based on the Clinical and Laboratory Standards Institute (CLSI), disk diffusion method, and confirmatory test (combined disk). Subsequently, polymerase chain reaction (PCR) was performed for following the relative genes. Results: The highest resistance in E. coli isolates was reported against ampicillin (56%), and 36% of samples were ESBL-positive. As determined by PCR, the prevalence of SHV, TEM, and CTX-M1 genes was 0%, 18%, and 38%, respectively. Conclusion: Due to the prevalence of β-lactamase genes, application of accurate and rapid identification methods such as PCR deems essential. Therefore, it can be considered as a routine method.