prevalence and molecular characterization of verotoxin-producing escherichia coli o157:h7 in cattle and sheep in shiraz-iran

shiga toxin producing escherichia coli have been associated with hus, hc and ttp in human. we found recto-anal mucosal sample in sheep as well in cattle is the main site for e. coli o157 localization. 1246 e. coli isolates from 872 both healthy and diarrheic animals were analyzed, by screening for the presence of shiga toxin-producing (vt 1 and vt 2) and intimin (eae) genes used multiplex pcr. 87(9.75%) vtec from 52 cattle and 28(7.90%) from 28 sheep were isolated. vt2 gene was found to be more frequent than vt1 in cattle (54.02% vs 26.43%), in contrast the same genes in sheep (21.42%vs25%). there was observed significant difference in the origin of vt positive sheep in close contact with farms of cattle origin. having cattle and sheep with each other was a possible risk factor. the animal was kept in pen was more localized than tethered. young cattle were documented strongly significant high prevalence rate in e. coli o157:h7 than older, but no effect of age was observed on the occurrence of e. coli o157 in sheep. both diarrheic and healthy animals were shed e. coli o157:h7 in their feces. sheep and dairy cow were not illustrated any significance differences geographical region and seasonal variation with e. coli o157:h7 prevalence rate.