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Various methods have been developed to detect the presence of contamination with Coliforms and E. coli in foods. The pour plate technique using VRBA medium is confirmed as a standard method in Iran. The biggest disadvantage of this method is the need to spend a lot of time, high volume of laboratory operations, multiple stages and ultimately long time to achieve the results. Today, due to the mass production of various foodstuffs, the need for faster methods with high sensitivity to control the quality of food is necessary for the responsible oversight centers. The use of chromogenic medias is also one of the fastest diagnostic methods that have been developed. According to this matter, a comparative study was considered from the results of application of three chromogenic media and reference method in food quality control. Totally 100 samples of foodstuffs were evaluated for contamination to Coliform and E.coli using standard method and three chromogenic medias. Based on the obtained results, 86, 79, 85 and 80 samples were contaminated to Coliform using the standard method, Coliform Agar ES, ChromAgar ECC and Rapid E.coli 2/Agar respectively. Also, using four mentioned methods, contamination to E.coli was reported at 66, 80, 84 and 80, respectively. Cochrane test showed that there was no significant difference between the four methods in Coliform diagnosis (p>0.05). However, four methods did not have the same function in the detection of E. coli so that the chromogenic methods showed significant difference with the standard method (p< 0/001). But there was no significant difference between these chromogenic methods in detecting E.coli (p>0.05). According to the statistical analysis of present study, three chromogenic medias can be used instead of the standard method for the detection of Coliform, but the use of these chromogenic medias is not recommended for the identification of E.coli. 

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Coliforms, especially Escherichia coli, are one of the most important causes of gastroenteritis and microbial index of water and food contamination. Enterohemorrhagic Escherichia coli strains are considered to be the most important intestinal pathogens due to hemorrhagic diarrhea and hemolytic syndrome, of which E. coli O157: H7 is the most important and common. The purpose of this study was to investigate the prevalence of E. coli O157: H7 contamination in traditional and homemade ice creams and compare the efficiency of chromogenic media with standard media for its detection. In this study, 90 samples of traditional ice cream from the production and distribution centers of this product were collected from three urban regions of Bandar Abbas, in two warm and cold seasons and in order to count the coliforms and detect E. coli and E. coli O157: H7, two standard and chromogenic methods were used. The results indicated that 81.8% of samples had more than the standard number of coliforms, and 28.9% of the samples were contaminated with E. coli. E. coli O157: H7 contamination was detected 2.2% and 4.4% using standard and chromogenic methods, respectively. Analyzes showed that application of media containing chromogenic substances, E. coli O157: H7 could be detected with the least possible error. It was found that the use of chromogenic culture media to identify E. coli O157: H7 was better than the standard method. The results of the present study also indicate that the quality and health status of traditional and handmade ice creams should be more closely monitored.