Quantification of viable Escherichia coli O157:H7 in meat products by duplex real-time PCR assays

Rapid and specific detection of viable Escherichia coli O157:H7 cells in ready-to-eat (RTE) meat products, by duplex quantitative PCR (qPCR) procedures with mRNA and SYBR Green and TaqMan methodologies were developed. Specific primers and probes were designed based on the serotype of E. coli O157:H7, fliCh7 and rfbE genes. No cross-reactivity with other microorganisms was observed. The detection limit of the assays was 101 or 102 CFU/g for artificially contaminated meat products, and after a 4 h enrichment period at 37 °C, the detection limit decreased to about 1 CFU/g. Time-to completion of the assay was approximately 8 h. Thus, these qPCR methods offer a useful, rapid and efficient tool for screening viable E. coli O157:H7 in RTE meat products. This tool could also be proposed for monitoring these foodborne pathogens in HACCP programs.