Study of the contamination of traditional cheeses produced in Maragheh city with Escherichia coli O157:H7

This study was conducted to determine the contamination of Escherichia coli O157: H7 in traditional cheeses in villages of Maragheh City. A total of 100 cheese samples were cultured in Tryptic Soy Broth containing cefixime and in Mac conkey sorbitol agar containing cefixime and potassium tellurite. Suspicious colonies were stained (Gram staining) and IMVC and other tests were performed on them. The isolated Escherichia coli were tested for detection of O and H serotypes by direct agglutination method. Cheese samples were also examined for pH and NaCl content. Antibiogram test was done on Escherichia coli isolates from cheese samples by Kirby-bauer’s method. According to the results، no case of E. coli O157: H7 was detected in the studied samples، although 32 cases of non O157 serotypes of E. coli including enteropathogenic (O55، O127، O86، O114، O44، O126، O125)، enterotoxigenic (O20، O128) and verotoxigenic (O26، O111) serotypes were identified. All of the isolated strains were resistant to Ampicillin and Polymyxin B. The effect of prevalence ratio of E. coli serotypes from pH and NaCl content was not significant statistically (p>0. 05). From the results of this study it is concluded that traditional cheese could be a potent carrier to transmit the various serotype of E. coli and cause disease in human.