Shiga toxin-producing Escherichia coli (STEC) strains have emerged as important foodborne pathogens of global public health concern, causing life-threatening diseases. Animal and their products have been documented as important reservoirs for STECs, especially E. coli O157. The aim of this study was to investigate STECs from healthy and diarrheal sheep in Sanandaj, Iran. In the current study, a total of 81 samples taken from sheep feces (22 samples from diarrheal sheep and 59 samples from healthy sheep). E. coli and subsequently STEC strain was detected according to standard protocol (cultural characterization and PCR assays). Finally, the frequency of Shiga-toxin producing gene(s) (stx1, stx2), intimin (eaeA) and enterohemolysin (hlyA) was detected among STEC isolates using duplex PCR. Totally, 42 E. coli were isolated from 81 fecal samples (51.85% contamination). Of these, 34 isolates (80.9%) were identified as STEC patotypes based on cultured on Sorbitol-MacConkey (SMAC) medium and also the presence of stx1 and/or stx2. Of these, only 3 isolates (7.1%) were identified as serotype O157:H7 based on PCR assay. In addition, the results showed that STEC bacteria were significantly detected in diarrheal samples than healthy samples (50% vs. 22.1%). Overall, the PCR results showed that 33 (97%), 12 (35.3%) and 8 (23.5%), isolates carried stx1, stx2 and hlyA, respectively. The eaeA gene was not found in any isolates. The number of isolated STEC bacteria in spring (10 isolates) and winter (14 isolates) and were significantly higher than summer (4 isolates) and autumn (6 isolates) (p=0.039). Also, the number of STEC bacteria in diarrhea samples was significantly higher than non-diarrhea samples (p=0.032). In conclusion, the present study revealed high prevalence rate of STEC bacteria including serotype O157:H7 and non-O157:H7 among sheep feces which highlight the importance of sheep as a reservoir of STEC pathogen in Sanandaj region. Therefore, the more control and preventive measures must be done to control the contamination by this pathogen.
