Shigatoxin-producing Escherichia coli (STEC) is a foodborne pathogen that can cause severe illness such as hemorrhagic colitis and hemolytic-uremic syndrome (HUS) in humans. US STEC illness estimates include 265,000 illnesses, 3,600 hospitalizations and numerous deaths annually. Fresh leafy vegetables have been implicated in many STEC foodborne disease outbreaks including a January 2018 outbreak suspected to be from romaine lettuce. The U.S. Food and Drug Administrationâs Center for Food Safety and Applied Nutrition (FDA- CFSAN) now uses Whole Genome Sequencing (WGS) and a Genome Trakr bioinformatics database as a highly effective regulatory tool to identify the specific source of foodborne outbreaks. One of hurdles that still needs to be addressed however is the difficulty in isolating specific pathogens from food where selective enrichment and slow culture isolation is still required. Direct to sequencing methods to include metagenomic sequencing for detection of STEC virulence genes directly from lettuce rinses are not possible especially for the detection of pathogens found in low copy and as a minor proportion of the total microbial load found on foods such as lettuce. VisuGen Global is advancing a novel approach to permit the sampling, concentration, and capture of NA found in dilute concentrations in large volumes of water or food rinses within a novel flow through NA capture chip (VisuChip). A cDNA copy of the captured NA can be made and transferred directly for sequencing. The objective of this phase I FDA-CFSAN SBIR is to confirm the feasibility of a using the VisuChip to capture and concentrate RNA released from microbes found in lettuce rinses and verify that VisuChip cDNA will interface with metagenomic STEC identification. Lettuce will be spiked with a STEC strain positive for virulence genes stx1, stx2, and eae then processed in parallel with VisuChip NA capture and DNA extraction by the FDA Bacteriological Analytical Manual (BAM) protocol at various enrichment times. We will compare turnaround time and limit of detection pre-enrichment and at various enrichment times following DNA 16S or metagenomic sequencing will be compared. The results of this Phase I work plan will verify the potential of VisuChip NA capture as a method to shorten STEC identification turnaround times, reduce enrichment and culture isolation requirements, and provide feasibility for direct sample processing to sequencing for processing lettuce. The approach could eliminate the need to ï¬rst isolate and culture a contaminating STEC strain in order to detect and characterize it. The impact will not only be more rapid leafy green outbreak tracking to protect public health but as an approach that could improve detection of other pathogens (Salmonella, Listeria) detection and other foods (meat and poultry, cheese, etc.). Additional application of VisuGenâs sequencing platform technology in human and veterinary, food and water disease address a greater than $100B market problem.
Public Health Relevance Statement: Narrative. Shigatoxin-producing Escherichia coli (STEC) is a foodborne pathogen that can cause severe illness in humans and fresh leafy vegetables have been implicated in many STEC foodborne disease outbreaks but current methods to isolate and identify the specific STEC pathogens takes days and are cumbersome. VisuGen Global LLC is developing a processing method using Nucleic Acid (NA) capture direct to sequencing to enable real-time STEC detection of contaminated leafy greens with rapid source identification and tracking to eliminate foodborne infection in this agriculture market. Additional application of VisuGenâs platform technology in human, veterinary, food and water disease address a $100B market problem.
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