Surveillance of Virulence Markers and Antibiotic Resistance of Shiga toxin Producing E.coli O157:H7 Strains from Meats Purchase in Shiraz

Shiga toxin Producing Escherichia coli O157:H7 is a common pathogen in cattle, which occasional causes some human disease. This bacterium can potentially contaminate meat and clinical cases of E.coli O157:H7 infections are often associated with consumption of undercooked ground beef. In this cross-sectional study 122 samples of ground meat were collected and after enrichment in specific culture media and evaluation sorbitol fermentation and their β-glucoronidase activity, the isolation of E.coli O157:H7 strains have been confirmed with specific antisera. Then virulence genes verotoxin, intimin and hemolysin with multiplex PCR and antibiotic resistance strains with disk diffusion method have been tested. Out of specimens that have been supplied, 119 sorbitol negative colonies isolated which 3 strains O157:H7 (2.45%) with specific antisera confirmed. Out of considered virulence genes, in two cases of these samples (1.64%) the stx1 and eaeA genes were seen and also 2 isolated bacteria had resistance to erythromycin, tetracycline, ampicillin, penicillin, clindamicin, cefixime, novobiocin, and gentamicin antibiotics. As this organism lives in intestines of healthy cattle, preventive measures on cattle farms and during meat processing are necessary.