GENE-UP® ECO PCR Method for the Detection of E. coli O157:H7 in Raw Meat and Produce

Introduction: E. coli O157:H7 is the most commonly E. coli strain associated with foodborne illness in beef and produce. Early detection of E. coli O157:H7 is essential in such foods with limited shelf life, this is why alternative rapid methods have been developed. Most PCR methods target E. coli O157 without any discrimination between non-pathogenic O157 and pathogenic O157:H7 strains. bioMérieux has developed GENE-UP® ECO for the specific detection of E. coli O157:H7.

Purpose: The study compares this alternative method to the ISO 16654:2001 Reference method for the detection of E. coli O157:H7 in raw meat and produce.

Methods: Ninety raw meat samples of 25 g and 375 g and 30 portions of 200 g produce were tested by both methods. The new method consists in a single BPW enrichment incubated at 42°C during 8 to 24 h depending on the food type and sample size. Then, DNA is extracted using mechanical lysis in a dedicated lysis tube: 15 µl are introduced through a cap that does not require any tube or cap handling. Extracted DNA is used directly with freeze dried PCR reagents. The PCR method is based on dual probe detection (Fluorescence Resonance Energy Transfer) allowing real time detection and melting curve analysis. The call is positive when it combines an amplification curve and a melting peak corresponding to the temperature defined exclusively for E. coli O157:H7, allowing a strong specificity of the test.

Results: Methods were compared following ISO16140 guidelines. The comparison did not show any statistical difference on the 120 samples tested.

Significance: Rapid (8 to 24 h enrichment) and specific detection of E. coli O157:H7 is made possible with GENE-UP® ECO in raw meat and produce for both 25 g and 375 g samples including a user-friendly workflow.