Public health aspects of Shiga toxin-producing Escherichia coli (STEC) strains in sheep and goats of Bakhtiari pastoral tribe, Iran

Nomadic populations do not have permanent settlements as they move their livestock between grazing areas in different seasons; such movements may have great impact on dissemination of food-borne pathogens in various regions. The aim of this study was to characterize Shiga toxin-producing Escherichia coli (STEC) strains as a food-borne pathogen in sheep and goats of Bakhtiari pastoral tribe in Iran. In the present study, 72 fecal samples were obtained from 26 sheep and 46 goats. First, all recovered E. coli isolates were screened for stx gene. After detection of stx -positive isolates, the virulence genes including stx1 , stx2 , eae , ehly , saa , astA , subAB , terD , and the genetic markers of O Island 57 (Z2098 and Z2099) were investigated. Also fifteen important STEC O-serogroups were determined using PCR assays. Results showed that 27 animals (27/72; 37.5%) carried STEC strains including 16/26 (61.6%) sheep and 11/46 (23.9%) goats. All STECs were eae -negative but 81.4% (22/27) were positive for saa . The most prevalent virulence profile was stx1 / stx2 / ehly / saa / subAB (37%; 10/27). Most STECs (24/27) were positive for at least one of the selected OI-57 markers. The O91 ( n = 6), O5 ( n = 3), O113 ( n = 1), O128 ( n = 1), and O104 ( n = 1) were the detected O-serogroups in this study. It is concluded that such moving animal populations could have public health concerns which have to be addressed in the future.