XX International Congress of Mediterranean Federation of Health and Production of Ruminants, 19-22 February (2013), Assiut University, Egypt Microbiological and Molecular Studies on E. Coli O157:H7 as one of Important Food Borne Diseases Mohamed Wael Abd Al-Azeem 1 , Asmaa A.A. Hussein 2 , Serageldeen Sultan 1 , Walled Khedr Mohamed 1 1 Faculty of Veterinary Medicine, Microbiology Department, South Valley University, Egypt 2 Faculty of Veterinary Medicine, Animal Hygiene and Zoonoses Department, Assiut University, Egypt Abstract E. coli O157:H7 and other verocytotoxigenic E. coli (VTEC) are zoonotic pathogens associated with food illness around the world. E.coli O157:H7 has emerged as an important gastrointestinal pathogen of man, which may give rise to serious clinical condition such as HUS and hemorrhagic colitis. The present study was undertaken to detect the E. coli O157:H7 in 200 samples (100 raw milk, 70 rectal swabs from apparently healthy & diarrheic calves and 30 stool samples from children). Raw milk and rectal swabs samples were collected from healthy & diarrheic calves from dairy farms and farmer houses in Qena Governorate and stool samples were collected from children suffer from diarrhea from clinical laboratory and General hospital in Qena Governorate. All samples were submitted for bacteriological examination, serotyping for detecting O157 using latex agglutination test and mo- lecular identification using uidA gene, SLT1, and fliCH7 gene. Sorbitol fermenter E.coli was isolated with a per- centage of 32%, 72.85% and 30% from raw milk, fecal samples of calves and stool samples of children, respectively. While, non sorbitol fermenter E. coli was isolated with a percentage of 6%, 2.85% and 16.7% from raw milk, fecal samples of calves and stool samples of children respectively. The overall occurrence of E. coli O157:H7 and E. coli O157: H- were 4/200 & 5/200 respectively. E. coli O157:H7 was isolated from two raw milk and two children stool samples with percentage of 1% and 6.7% using PCR respectively. E. coli O157:H- was isolated from raw milk, rectal swabs and stool samples of children with a percentage of 2%, 1.42% and 6.7% re- spectively. Our results indicated that polymerase chain reaction (PCR) still the more specific and sensitive method as a rapid technique and raw milk carry a risk of E. coli O157:H7 and consider as a vehicle of transmission to man. Keywords: E. Coli O157:H7 , food borne diseases, milk, calves, children Introduction Escherichia coli (E. coli), a bacterium that is a common inhabitant of warm blooded animals gut, including man. Most strains of E. coli are harmless; however, some strains such as E. coli O157:H7 can cause severe food borne disease and are referred to as enterohemor- rahgic E .coli (WHO, 1996). E. coli O157:H7 is one of hundreds of gram negative E. coli and is the most well known enterohemorrahgic strain (EHEC) (Peacock et al. 2001). The letter "O" in the name refers to the somatic antigen number, whereas the "H" refers to the flagellar antigen (Nataro and Kaper, 1998). E. coli O157:H7 serotype occurred due to the hori- zontal gene transfer of virulence factors (Whit- tam et al., 1988). E .coli O157:H7 was first recognized as a human pathogen in 1982, when two outbreaks in the United States were associated with eat- ing undercooked hamburgers from a fast-food restaurant chain (Riley et al., 1983). This food borne pathogen has since emerged as a major cause of bloody and non bloody diarrhea, causing up to 20,000 cases and up to 250 deaths per year in the United States (Griffin, 1995). In addition to causing bloody diarrhea, E .coli O157:H7 infection is the most common cause of the hemolytic uremic syndrome (HUS), which cause kidney failure among chil- dren in the United States (Siegler et al., 1994). The verocytotoxigenic E. coli (VTEC) enter the food chain via fecal contamination of milk, contamination of meat with intestinal contents during slaughter or contamination of fruit and vegetables by contact with contaminated ma- nure. It is also transmitted through contact with infected people, animals or animal waste. Moreover, contaminated water which used for irrigating or washing vegetables can also be source of infection for humans or animals (Paton and Paton, 1998). Routine techniques for diagnosis of VTEC focus exclusively on the detection of E. coli 13