Prevalence of Escherichia coli O157:H7 in bovine feces in North West of Iran

Abstract

The objective of this study was to identify and estimate the prevalence of Escherichia coli O157:H7 in cattle fecal samples in northwest of Iran, using multiplex polymerase chain reaction (PCR). In this study, cattle fecal samples were collected from an abattoir in Tabriz, Iran. After enrichment, isolation was carried out on CT-SMAC culture and afterwards, the identification of E. coli O157 was achieved on colorless sorbitol negative colonies. Then, one of these colonies was analyzed by PCR to identify genes coding for verotoxin 1 and 2 (vt1 and vt2), intimin (eceAO157), and H7 flagella antigen (fliCh7). Of 200 samples, 22 were positive by CT-SMAC culture. Of the 22 sorbitol-negative samples investigated by PCR, two isolates were identified as E. coli O157:H7. Three isolates carried eaeAO157 specific locus (non-VTEC E.coli O157) and one or both the verotoxin genes (vtx1 and vtx2) only (non-O157 VTEC). Low prevalence rates of E. coli O157:H7 in cattle feces as an important animal reservoir of the mentioned bacterium should be added to the variety of factors mentioned for the low prevalence of E. coli O157:H7 in Iran.