نوع مقاله : مقاله های پژوهشی
1 دانشیار، گروه میکروبیولوژی، دانشگاه آزاد اسلامی واحد جهرم، جهرم، ایران
2 کارشناسی ارشد، گروه میکروبیولوژی، دانشگاه آزاد اسلامی واحد جهرم، جهرم، ایران
3 کارشناسی ارشد، گروه میکروبیولوژی، دانشگاه آزاد اسلامی واحد مرودشت، مرودشت، ایران
عنوان مقاله [English]
Background: Escherichia coli O157:H7 have emerged as pathogens that can cause food-borne infections and severe illnesses in humans, such as hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS). Since this bacterium is transferred by the foodstuff, especially hamburger it is called "hamburger bacteria". The aim of this study was isolation and identification of E.coli O157:H7 from hamburger samples in Shiraz, Isfahan.Methods: In this cross- sectional study, 320 samples of Hamburger were collected and enriched in TSB with novobiocin medium in 37ºC temperature. Fermentation of sorbitol and lactose and activities of β-glucoronidase of separated bacteria were examined by using the SMAC and VRBA media and choromoagar medium. Then the existence of E.coli O157:H7 was confirmed with the specific antiserum. At the end existence of virulence genes and antibiotic resistance strains were tested with multiplex PCR and disk diffusion methods.Findings: Out of all examined samples, 259 (80.93%) sorbitol negative bacteria were separated. From which 227 (87.64%) had ability of lactose fermentation. Then by using biochemical tests, 192 samples (84.58%) were identified as E.coli. Also the rate of recognition of MUG negative and E.coli O157:H7 were 50.00% and 3.43% respectively. By evaluation of virulence markers, eae and stx1 genes were identified in 3 samples and eae, stx1 and stx2 identified in 1 sample. Also in 1 sample only hly gene was detected. All isolated strains were resistant to most antibiotics. Conclusion: Since this bacterium is an high risk pathogene and hamburger was a common source in recent outbreak, monitoring of all kinds of meat products is recommended.