Table of contents Introduction History Characteristics Mechanism of action Factors affecting growth Toxins Symptoms Transmission Complications Epidemics Food association Diagnosis Disinfectants Treatment Vaccination Preventions  References Enterohemorrhagic Escherichia coli Introduction E.coli is a Gram-negative bacterium present in the form of rods (bacilli) in the Enterobacteriaceae. Most of the time, E. coli are normal commensals of the intestines, which allows the isolation of pathogenic strains based on virulence factors, e.g. toxins. The EHEC group produces shiga-like toxins (stx), enterohemolysin, and intimate adhesion factor (Intimin). SerotypesE.coli serotypes based on O (somatic polysaccharide), H (flagellar) and K (capsular) antigens. EHEC serotypes include E.coli O157:H7 and others O26, O103, O111, O145. Research studies only show a small number of cases. 10 to 100 microbes are enough to cause an infection. History of EHEC In 1982, E.coli O157:H7 was first identified as causing bloody diarrhea from eating undercooked or contaminated raw hamburger. The infection was first recognized by the CDC. separates two outbreaks in Oregon and Michigan from eating hamburgers at national chain restaurants. Patients experienced hemorrhagic colitis (inflammation and bleeding of the colon) due to E.coli O157:H7, called hamburger disease . Characteristics• E.coli O157:H7 is a main serotype associated with hemorrhagic colitis• It does not ferment sorbitol and has no glucuronidase activity compared to other E.coli strains.• It grows rapidly at 30-42°C, weak growth at 44-45°C and shows no growth at 10°C.• It is resistant to pH 4.5...... middle of paper ......., and Ammar, MS1993. Survival and growth of Escherichia coli O157:H7 on salads. Appl. Approximately. Microbiol.59: 1999–2006. Ahmed, NM, Conner, DE and Huffman, DL 1995. Heat resistance of Escherichia coliO157:H7 in meat and poultry as a function of product composition. J.Food Sci.60:606-610.Doyle, MP, Escherichia coli 0157:H7 and its importance in foods, lilt. J. Food Microbiol., 12,289,1991.Donnenberg, MS and Whittarn, TS, Pathogenesis and evolution of virulence in enteropathogenic and enterohemorrhagic Escherichia coli, J. Clin. lnv., 107(5),539, 200l.Anonymous, FSIS background of Escherichia coli update: E. coli 0157:H7, Media Relation Office,Food Service and Inspection Service, USDA, January 1993.FUNDAMENTALFOOD MICROBIOLOGY FOURTH EDITION