Shiga toxin Escherichia coli (STEC) are associated with human intestinal infections. Enterohaemorrhagic E. coli (EHEC) is a subset of STEC, it includes highly virulent strains associated with human Haemorrhagic Colitis and Hemolytic Uremic Syndrome. Cattle are an important source of STEC/EHEC contamination in the food chain. The study objective was to assess the prevalence and risk factors for STEC/EHEC carriage in cattle in Israel. A total of 1,400 stool samples were collected from 46 farms, including dairy and beef cattle from different age groups and farming systems. Samples were tested by PCR for genes stx1 and stx2 (STEC), and eae (EHEC). Overall, STEC and EHEC prevalence was 62.6% and 35.8%, respectively. Significant differences in prevalence were found between different cattle populations and farming systems. Among farm-related risk factors found were geographic location (higher prevalence in south vs. center and north) and farm type (higher prevalence in dairy vs. beef farms). Among group-related risk factors found were animal density (prevalence increased with density) and age (higher prevalence in young cattle). A total of 170 STEC isolates were obtained from a subset of 600 positive samples. Genotyping was performed for the most important antigen-O types (O157, O111, O103, O121, O145, O26 and O45). Seven isolates were O157 (two O157:H7), one O45 and one O26. Results suggest that cattle could be a source of STEC/EHEC in Israel. However, prevalence of major human pathogenic serotypes at farm level is low. Further studies are needed to investigate risk factors at abattoirs and food-processing plants level.
