Genetic Diversity of Escherichia coli O157:H7 strains using random amplified polymorphic DNA (RAPD)

Escherichia coli O157:H7, an emerging cause of food-borne disease, has now been reported from several countries worlwide. Cattle and sheep are known as a principle reservoir of this agent. It is also prevalent in gastrointestinal tract of other animals like pigs, dogs, cats and birds. This agent can be transmitted to humans by food and water and even person to person contact. The random amplified polymorphic DNA (RAPD) technique has been applied to evaluate zoonotic potency of Escherichia coli O157:H7 local isolates. Ten random decamer primers have been evaluated in this study to differentiate isolates originated from humans and animals. The OPA-02, OP-03, OPA-04, OPA07, OPA-08, OPA-09, OPA-10, OPA-13, OPA-19, and OPA-20 decamer primers show a good differentiation pattern of E. coli O157:H7 isolated from human, cattle and chicken feces, as well as from beef. The primers constantly produce 16, 16, 11, 14, 8, 24, 7, 11, 7, and 12 polymorphic bands, respectively. Various human isolates that were isolated from clinically ill and healthy patients share common genetic clusters with animal isolates from beef, as well as cattle and chicken feces with genetic similarity coefficients greater than 70%. According to this result, It has been concluded the transmission of E. coli O157:H7 local isolates from animals to humans is potential occur.