Monday, August 4, 2014
Exhibit Hall D (Indiana Convention Center)
Introduction: The BIG 7 Shiga toxin-producing Escherichia coli (STEC) which includes stx+ and eae+ strains from major serogroups O26, O45, O103, O111, O121, O145, and O157:H7 are classified as beef adulterants by the USDA FSIS. The food industry relies on rapid and sensitive methods to detect these pathogens, thus ensuring a safe supply of foods. Current approved PCR screening methods show high false-positive rates in detecting pathogens. PathoGenetix’s automated Genome Sequence Scanning (GSS) system is developed to rapidly and accurately identify pathogens within five hours from enriched samples. GSS system generates restriction DNA fragments from target strains which are fluorescently labeled with sequence-specific probes. The labeled DNA molecules are then linearized within a microfluidic chip, passed through spots of focused laser light, and their fluorescence measured. These sequence-specific optical patterns generated from the genomic DNA fragments are compared to a template database containing more than 500 E. coli strains for pathogen identification.
Purpose: To demonstrate typing of BIG 7 STECs directly from produce and meat following enrichment that is compatible with current USDA and industry practices.
Methods: We spiked 25 g samples of spinach or ground beef with TMSTEC plates, respectively.Results: Of the 96 samples spiked with a strain of STEC, 93 samples (97%) were confirmed to be positive for the correct strain. No false positives were detected.
Significance: The data demonstrates that GSS correctly identifies all BIG 7 STECs in two different matrices using commercial and USDA/FDA recommended workflows.