As regulations for Listeria, Salmonella and E. coli O157:H7 tighten and consumer demand for fresh product increases, many companies find themselves searching for new ways to release product faster without compromising safety. Washington Beef, a beef processor in Toppenish, WA, has found an ideal solution in Assurance GDS, a new DNA-based pathogen detection system from BioControl. The Assurance GDS system combines the latest advancements in molecular technology and food microbiology to provide the speed, simplicity, sensitivity, and specificity required by organizations such as Washington Beef to meet today’s pathogen detection and operational challenges.
In business since 1979, Washington Beef’s success is largely due to their ability to schedule, process and package product to a customer’s exact specifications and deliver it in just two days. “This business model has become increasingly more difficult to support, especially with the implementation of USDA’s new Test and Hold policy,” says Hipolito Hernandez, Washington Beef’s microbiologist. “Nothing can leave the plant without a negative test result.”
To meet this need, Washington Beef turned to BioControl’s new Assurance GDS™ (Genetic Detection System), a DNA based system for the rapid detection of food pathogens. BioControl Inc. is a worldwide leader in food safety testing solutions (www.biocontrolsys.com). “A key advantage that Assurance GDS has over other pathogen detection systems is that its design includes three levels of specificity,” says Geoff Bright, BioControl microbiology product manager. These include immunomagnetic separation (IMS), highly specific primers and a patented probe system that ensure the highest degree of accuracy. “The multiple levels of specificity have enabled us to overcome matrix interference and cross reactivity—issues that are common to other antibody and genetic based systems,” says Bright. “The benefit to customers is achieving consistent and accurate results hours faster than other methods.”
Superior Specificity Leads to Faster, Fresher Product Release
For Hipolito and his team, Assurance GDS™ provides the ideal solution combining speed and accuracy. “Prior to GDS, our lateral flow test gave us results almost immediately after enrichment but we were struggling with false-positive rates as high as 15-20% during the warmer periods of the year,” says Hernandez. A primary difference between the antibody-based lateral flow and Assurance GDS is the inability of the antibody technology to distinguish between the target organism and others possessing a similar antigen. Assurance GDS, however, targets a highly specific DNA sequence unique to the target, ensuring greater specificity.
“Prior to Assurance GDS we could not justify adopting a DNA-based method because they simply were not fast enough,” Hernandez adds. “Now, with GDS we can get results as fast as we could with the lateral flow but with the specificity we need.”
Assurance GDS for E. coli O157:H7 offers results in eight hours. With a six-and-a-half hour enrichment and only 70 minutes of cycling time, results are available within a single eight-hour shift. “The Assurance GDS Rotor-Gene™ cycler is so fast, you can process multiple sets of samples in the time it takes other PCR systems to complete a single run,” Hernandez says. While traditional systems cycling times and melt-curve analysis can take up to four hours or more, Assurance GDS utilizes an innovative rotary based instrument that eliminates the need for melt curves and is therefore over 100 percent faster.
The advantages of a system not reliant on melt curves are evidenced not only in the speed of Assurance GDS, but also in its ease of use and accuracy. “Melt curves can be difficult to interpret and can lead to subjective determination of results,” according to Bright. “Assu-rance GDS on the other hand offers distinct, pass/fail results that require no interpretation by the user. If the target organism is present, the test result is positive. It is that simple.”
The benefits of GDS superior specificity were realized almost immediately at Washington Beef. “Confirmation of a positive can cost us over $135 per sample and take up to five days. Because of the constraints on fresh product shelf-life, we were often forced to convert it to frozen product, which has a lower market price, while waiting on these test results. Now, our ability to consistently and confidently release fresh product provides the sales department with a lot more flexibility to meet customer demand and has eliminated the need for the shipping department to unnecessarily shift loads or change orders in response to false positives,” Hernandez says.
“I am very pleased with the performance of the GDS system and look forward to being able to run our Salmonella and Listeria tests on the same platform soon,” he adds. While E. coli O157:H7 and ShigaToxin(s) are the first assays developed on the Assurance GDS platform, assays for Salmonella, Listeria and L. mono are expected to be released by BioControl later this summer.