Detection of Escherichia coli O157:H7 in Food

Abstract

The present study aims to estimate the presence of Escherichia coli O157:H7 as a contamination indicator in beef meat, dairy products and different types of ready food in local markets at Baghdad city. Sixty one samples of different food samples were tested. One isolate was detected, E. coli O157:H7 on differential and selective media MacConkey agar, sorbitol MacConkey agar, chromogenic media and routine biochemical tests were used to diagnose and identify the bacteria of other members of enterobacteriaceae. Seven isolates of E. coli were confirmed on Hi Crome EC 0157:H7 selective agar as E. coli 0157:H7, then results showed one isolate sorbitol negative carrying Shiga-like toxins (SLT)2 was detected by PCR as E. coli O157:H7, during experiments another isolate was sorbitol positive also carried SLT2. The duplex PCR procedure did not detect the SLT1 sequence in any of the contaminated samples, but found SLT2 genes in one of them. The current study supported that the presence of E. coli O157:H7 is low in food.