الفهرس 
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Abstract
Verotoxin-producing Escherichia coli (VTEC) is a zoonotic pathogen that causes diarrheal disease in humans which may progress to serious complications and death. In this study we investigated the occurrence of VTEC in farm animals and humans in some localities in Egypt. A total of 721 samples that included 463 faecal and 132 milk samples were collected from buffaloes, cattle, sheep and goats as 40, 155, 192 and 76 faecal samples and 30, 33, 34 and 35 milk samples, respectively. Also included 96 carcass swabs that were collected from slaughtered buffaloes and dairy cows. Also 30 faecal samples were collected from diarrheic calves in a dairy farm with suspected VTEC outbreak. On the other hand, 100 humans’ stool specimens were obtained from 42 and 51 patients living in urban and rural areas, respectively, and 7 apparently healthy workers in the dairy farm with suspected VTEC ourbreak. Samples were screened with ELISA to detect verotoxins (vtx), and then positive samples were cultured onto selective chromogenic medium for VTEC. Afterwards, positive isolates were proved as E. coli after being subjected to cultural and biochemical tests and confirmed molecularly by the polymerase chain reaction (PCR) for the presence of verotoxin-encoding genes. The occurrences of VTEC in faeces of animals were 45.0%, 17.4%, 2.6% and 2.6% and in milk were 0.0%, 3.0%, 2.9% and 0.0% for buffaloes, cattle, sheep and goats, respectively. No VTEC was recovered from the 96 carcass swabs. A total of 27 out of 30 calves (90.0%) were found VTEC-positive in that dairy farm. Additionally, 5 (9.8%) stool specimens from the individuals living in rural areas and all 7 farm workers were found positive for the presence of VTEC, while none of the urban individuals were found VTEC-positive. It is noteworthy that, according to O157 latex agglutination test, only one isolate recovered from dairy cow’s milk was proved to belong to E. coli O157 serogroup. This study demonstrated the role of buffaloes as an overlooked reservoir for VTEC, illustrated the higher risk of VTEC infection to humans who are in contact with farm animals and highlighted the shift in predominance from O157 to non-O157 VTEC.