AN IMPROVED PROCEDURE FOR THE DETECTION OF ESCHERICHIA-COLI O157 IN FOOD USING AN AUTOMATED SCREENING METHOD

Three enrichment schemes for detection of Escherichia coli O157 in foo d were evaluated for sensitivity using an automated screening method. Two pre-enrichment broths, modified tryptone soya (mTSB) and modified Escherichia coli (mEC) were compared as well as a secondary enrichment step using a Mac Conkey based media. The combination of enrichment in modified tryptone soya broth (mTSB) incubated at 42 degrees C for 6 h and the use of a Mac Conkey broth containing cefixime and tellurite ( CT-MCB) for 18-24 h at 37 degrees C prior to performing the automated immune-assay has proved to be the most sensitive procedure and increas ed the specificity of the immunoassay screening method.