INVESTIGATION OF FREQUENCY AND VIRULENCE GENES OF TYPICAL AND ATYPICAL ENTEROPATHOGENIC ESCHERICHIA COLI (EPEC) AND SHIGA TOXIN –PRODUCING ESCHERICHIA COLI (STEC) IN BIOLOGICAL SAMPLES

Background and Aim:Foodborne diseases are a major public health problem with growing concern.The contamination of food by enteric pathogens such as EPEC and STEC is an important cause of diarrheal disease in worldwide. E.coli has been isolated from food such as vegetables,meat,seafood ,fruit and from milk.EPEC strains are classified as typical and atypical according to the presence or absence of bfp-A and eae genes.Typical EPEC a leading cause of infantile diarrhea in developing countries,and atypical EPEC is responsible for sporadic outbreak in developed country.STEC have been implicated as the causative agent in several human diseases including mild nonbloody or sever bloody diarrhea,Hemolytic Uremic Syndrome(HUS) and renal failure.Methods:In this research One hundred raw beef and forty milk samples collected in Tehran and alborz during November 2017 to May 2018,and were transported to the laboratory. Beef samples homogenized by stomacher in EC broth containing cefexime.Milk samples inrichmented in EC broth containing cefexime.so all samples culture on MacConkey agar medium.Bacterial DNA was extracted by boiling method and PCR was done for eae A,bfp, stx1 and stx2 genes .Biochemical test were done to confirm Ecoli.Results:Pcr analysis showed that four of these isolates were atypical EPEC positive and six were STEC positive(nine of raw beef & one milk).All positive isolates were confirmed by biochemical tests as E.coli.Conclusion:This research show that raw beef and milk may be the source of EPEC and STEC infection,and could be as a vehicle for transmission of diarrheagenic E.coli.

کلیدواژه ها:

Enteropathogenic e.coli ، Shiga toxin –producing E.coli ، Raw beef ، Milk ، Pcr