Bio-Rad launches droplet digital PCR kit for STEC detection in food safety testing

Bio-Rad Laboratories, Inc. has announced the launch of its dd-Check STEC Solution for detecting virulence genes from Shiga toxin-producing Escherichia coli (STEC). Pathogenic STEC is defined as the presence of both stx1 and stx2, as well as eae, in one E. coli bacterium. The kit, which harnesses Bio-Rad’s Droplet Digital PCR (ddPCR) technology, is the first commercially available test for determining the coexistence of the STEC virulence genes in a single bacterium, providing rapid and reliable confirmation of the presence of pathogenic STEC.

Traditional screening tests for pathogenic STEC cannot distinguish between bacteria carrying both virulence markers (true positive) and mixed cultures in which these target genes are present in different bacteria (false positive). After a traditional screening test, samples must go through laborious culture methods to confirm results, which can take up to five days.

Since dd-Check STEC Solution accurately determines the coexistence of stx and eae in the same bacterium without additional confirmatory steps, it can return results in a few hours. Decreasing screening and confirmation turnaround time means products can be released to market faster, which is especially important for food matrices with limited shelf life.

The dd-Check STEC Solution uses ddPCR technology to generate thousands of uniform nanoliter-sized droplets. Once generated, the droplets can be amplified, read, and analyzed for the colocalization of virulence genes by Bio-Rad Qx IDE Manager Software. By encapsulating a single bacterium in each droplet, the dd-Check STEC Kit can distinguish between a true positive and a negative result.

As regulations classifying STEC as an adulterant continue to change, the kit provides the flexibility to adapt to new requirements. If other virulence factors are required for testing, the workflow can be updated to include additional testing.

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