Droplet Digital PCR (ddPCR) employs advanced microfluidics technology to generate thousands of highly uniform nanoliter-sized droplets in each sample, achieving sample partitioning on a massive scale. Once generated, the droplets can be amplified, read, and analyzed. In traditional PCR, a single measurement is performed on a single sample, while in Droplet Digital PCR, thousands of measurements can be performed on each sample.

■■ Next-day confirmation results■■ Fewer presumptive positives than with PCR■■ Useful for various food safety applications, such as colocalization, genetically

modified organism (GMO) testing, food fraud, bacterial monitoring, pathogen enumeration, and virus detection

Droplet Digital PCR for Food Testing

Droplet Digital PCR: Food Safety

Visit bio-rad.com/ddcheck for more information.

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Principle of Colocalization Colocalization can be used to accurately detect enterohemorrhagic Escherichia coli (EHEC), which is a highly pathogenic subset of Shiga toxin–producing E. coli (STEC), in a variety of food matrices.

Food with a single E. coli bacterium that carries both the stx gene for Shiga toxin production and the eae gene for the intimin attachment protein is positive for EHEC. This can be challenging for other technologies to distinguish. Droplet Digital PCR is able to encapsulate bacteria inside each droplet, making it possible to accurately detect an E. coli bacterium carrying both virulence genes.

dd-Check STEC Solution The dd-Check STEC solution uses ddPCR technology to distinguish bacteria with true, double-positive linked virulence genes in a sample from bacteria containing single-positive or unlinked virulence genes, reducing the number of false-positive STEC results. This detection and linkage verification of targets in a single bacterium enhances the accuracy of pathogenic E. coli testing.

Gray: Droplets negative for both targets

Orange: Droplets positive for both stx and eae

Blue: Droplets positive for stx only

Green: Droplets positive for eae only

Qx IDE Manager SoftwareThe Qx IDE Manager Software was designed specifically for food safety applications. It provides complete automated analysis for the dd-Check STEC Kit assay. Results interpretation is based on the presence or absence of the two targets (stx and eae) and on the linkage analysis showing the colocalization of these virulence genes coming from a single bacterium.

Thousands of measurements Amplification by PCR

PCR is performed with a thermal cycler, and droplets containing target DNA

are now fluorescent

Food samples are enriched to allow for growth of target bacteria

An excess of double positives reveals the presence of two markers on the same genome, which can be statistically established (percentage linkage).

One sample

Target of interest (eae)

Target of interest (stx)

Background DNA

Target of interest (stx + eae)

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Oil

Oil

Droplets

Sample

■■ Enrich sample in 16–24 hr ■■ Filter and concentrate sample

■■ Load the filtered sample, ddPCR reaction mix, and oil into the wells of a droplet generator cartridge

■■ 8 x 20,000 droplets are generated from each run in the QX200 Droplet Generator

■■ Transfer the droplets to a 96-well PCR plate and seal the plate

■■ Run the PCR protocol

■■ After PCR, load the 96-well PCR plate into the QX200 Droplet Reader

■■ Analyze linkage with Qx IDE Manager Software

Enrichment and Sample Preparation1

Generate Droplets2

Perform PCR3

Read Droplets and Analyze Results4

dd-Check STEC WorkflowThe dd-Check STEC workflow is scalable to allow users the flexibility to test 1 to 94 samples per plate. Laboratories can use the dd-Check STEC solution as an initial screening tool or after screening with the iQ-Check STEC Kits for next-day confirmation of pathogenic E. coli.

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Ordering InformationCatalog # Description

17004826 dd-Check STEC Solution, includes kit and oil12010000 dd-Check STEC Droplet Generation Oil 12009999 dd-Check STEC Kit 3554179 Buffered Peptone Water Broth, 6 bottles x 225 ml 3564684 Buffered Peptone Water Broth, 500 g 3564005 Selective STEC Supplement, 1 g 3578139 iQ-Check STEC VirX PCR Detection Kit 3578140 iQ-Check STEC SerO PCR Detection Kit 3600037 CFX96 Touch Deep Well Real-Time PCR Detection System 17005228 QX200 Droplet Reader

Bio-Rad, ddPCR, and Droplet Digital PCR are trademarks of Bio-Rad Laboratories, Inc. in certain jurisdictions.

The QX200 Droplet Digital PCR System, and the consumables and reagents designed to work with this system, and/or their use is covered by claims of U.S. patents and/or pending U.S. and non-U.S. patent applications owned by or under license to Bio-Rad Laboratories, Inc. See bio-rad.com/en-us/trademarks for details. Purchase of the product includes a limited, non-transferable right under such intellectual property for use of the product for internal research purposes in the field of digital PCR only. No rights are granted for diagnostic uses. No rights are granted for use of the product for commercial applications of any kind, including but not limited to manufacturing, quality control, or commercial services, such as contract services or fee for services. Information concerning a license for such uses can be obtained from Bio-Rad Laboratories. It is the responsibility of the purchaser/end user to acquire any additional intellectual property rights that may be required.

All trademarks used herein are the property of their respective owner.

QX200 Droplet Reader and Generator

Droplet Generation Oil

dd-Check STEC Kit

CFX96 Touch Deep Well Real-Time PCR Detection System

Catalog # Description

17005227 QX200 Droplet Generator 17005230 Laptop for QX200 Droplet Digital PCR System 17005226 PX1 PCR Plate Sealer 17005221 ddPCR Droplet Reader Oil, 2 x 1 L 17005222 DG8 Cartridges for QX200 Droplet Generator, package of 24 17005223 DG8 Gaskets for QX200 Droplet Generator, package of 24 17005224 ddPCR 96-Well Plates, semi-skirted, 25 17005225 Pierceable Foil Heat Seals 1863051 DG8 Cartridge Holder