Bacterial Identification System Differentiates Virulent “Big 6” E. Coli Strains in Five Hours

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Research presented at the Association of Public Health Laboratories meeting this week shows that PathoGenetix's Genome Sequence Scanning (GSS) can identify pathogenic E. coli strains directly from complex mixtures and shorten the time for pathogen subtyping to five hours. New data also shows that GSS has the potential to differentiate the “Big 6” STECs from less virulent non-STEC Big 6 serovars encountered in the same sample.

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The ability of GSS to reliably differentiate virulent STECs means that the system could be used as a confirmatory method for Big 6 STEC screening assays, and potentially reduce the loss of product associated with false positive results...

PathoGenetix, Inc., developer of an automated system for rapid bacterial identification, has presented new research demonstrating the use of Genome Sequence Scanning™ (GSS™) to identify and differentiate virulent Shiga toxin-producing E. coli (STEC) strains directly from enriched food samples in five hours. The results, which were detailed in a poster presented at the Association of Public Health Laboratories (APHL) Annual Meeting on Sunday, have significant implications for food producers required to test their products for pathogens with certain virulence characteristics, and for public health agencies needing to quickly identify and find the source of foodborne illness outbreaks.

The research tested representative strains of the pathogenic “Big 6” STECs, which contained the stx and eae virulence genes, as well as non-STEC Big 6 E. coli, on PathoGenetix’s Genome Sequence Scanning system. GSS successfully identified and differentiated each serovar of the Big 6 STEC E. coli. In addition, preliminary data showed the potential to differentiate Big 6 STECs from Big 6 E. coli of the same serotype that do not possess the stx and/or eae virulence genes. The current criteria for determining the presence of a Big 6 pathogen is the identification of the presence of both of these virulence genes in a Big 6 serovar.

The most common STEC serotype is O157:H7, which food producers have been testing for since 1994. Last year, the U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) added six additional pathogenic E. coli serotypes (O26, O45, O103, O111, O121 and O145) to its list of food adulterants that it requires meat producers to test for in certain beef products.

Current screening methods have a high “false positive” rate for virulence due to the commingling of virulence factors that can be present in an enriched food sample. The ability of GSS to reliably differentiate virulent STECs means that the system could be used as a confirmatory method for Big 6 STEC screening assays, and potentially reduce the loss of product associated with false positive results from current STEC screening tests.

The automated GSS system extracts, scans and analyzes microbial DNA directly from a complex sample to provide bacterial serotype and strain type results in five hours. The bacterial strain information provided by GSS is comparable to pulsed field gel electrophoresis (PFGE), the current standard for pathogen typing in foodborne illness outbreak investigations. Unlike PFGE however, GSS does not require pure culture isolates and thus is compatible with newer pathogen detection methods in use in clinical and food industry laboratories. Genome Sequence Scanning will be commercially available in 2014 as the RESOLUTION™ Microbial Genotyping System.

About PathoGenetix, Inc.

PathoGenetix, Inc. is a commercial-stage developer of an automated system for rapid bacterial identification from complex samples. PathoGenetix is a venture-backed company that has received more than $50 million in technology development funding from the Department of Homeland Security. The core GSS technology isolates and analyzes DNA directly from an enriched biological sample—without the need for a cultured isolate—and provides results in just five hours, days faster than current methods. GSS has broad applicability in food safety, industrial microbiology, and clinical diagnostics and research. The first commercial GSS system will be available in 2014 for use in food safety testing and foodborne illness outbreak investigations. Learn more at http://www.pathogenetix.com.

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Mary Hawkins
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