Food Safety Magazine

SOLUTIONS IN RAPID MICROBIOLOGY | October/November 2009

Rapid Pathogen Detection Method Helps Lab Meet Customer Needs

By BioControl Systems

Rapid Pathogen Detection Method Helps Lab Meet Customer Needs

Whether conducting testing in-house or choosing to contract with an independent reference lab, food processors’ decisions regarding pathogen detection technology and methods play a critical role in their overall food safety program. As a respected microbiology reference lab, TRAC Microbiology of Madison, WI strives to provide customers with the fastest and most accurate pathogen testing results possible. Recently, the lab was faced with a need to upgrade its pathogen detection technology for Salmonella, Listeria, E. coli O157:H7 and Enterobacter sakazakii.

“As market pressures continue to increase, our customers look to us to help them meet their food safety objectives—quickly, with a high degree of sensitivity and with AOAC-approved methods. In the area of pathogen detection, classic cultural methods and even many of the rapid methods no longer meet our customers’ needs,” says Virginia Deibel, TRAC Microbiology CEO. “However, advancements in genetic detection technologies have enabled TRAC to provide the highly accurate next-day results our customers require to remain competitive.” After conducting extensive research and comparing multiple pathogen detection technologies, TRAC decided to invest in the Assurance GDS™ pathogen detection system from BioControl Systems, Inc., a Bellevue, WA-based leader in food safety testing.

Market Demands Accuracy and Next-day Results
When Matt Howard, genetic scientist at TRAC Microbiology, began looking to improve the lab’s pathogen detection program, he knew where to start. “I needed a system that we could be confident would give us accurate results for a full array of pathogens across a wide variety of sample matrices,” explains Howard. “When you combine that with the market demand for next-day test results, it immediately narrowed the field to PCR-based systems.” Because PCR directly targets and amplifies a specific DNA sequence of an organism, it is widely accepted as the most specific and sensitive detection technology currently available.

Due to the critical nature of pathogen testing in food samples, accuracy was at the top of TRAC’s list of performance criteria for TRAC. Thanks to Howard’s background in genetics and past experiences with PCR, he was able to further narrow the list of candidates. “We definitely needed a system that combined the specificity of both primers and probes. Because probes provide sequence-specific detection of the amplified DNA and melting-curve systems rely on non-specific dyes such as SYBR Green, I knew we could have greater confidence in results from a probe-based assay,” he states. “Additionally, results from a probe-based system don’t require the subjective interpretation often necessary to determine the results of melting curves.”

Performance Factors Essential in Method Selection
However, there were many other factors that had to be considered before making a final decision, including AOAC approvals, ease of use, reliability and of course, cost. While some systems were able to satisfy one or two of these requirements, Assurance GDS proved to be the only system that could satisfy all of TRAC Microbiology’s stringent performance criteria.

The system takes advantage of advances in sample preparation techniques and molecular biology to provide a high degree of accuracy. The system provides three levels of specificity, which include immunomagnetic separation (IMS) during sample preparation to concentrate the sample and remove PCR inhibitors, highly specific primers and patented DNA probes, which ensure accurate detection of the target organism. Combined, these features provide the accuracy that TRAC personnel were looking for.

The single-step enrichments and simple sample-prep procedures of the Assurance GDS system produce a streamlined workflow that was easily implemented in TRAC’s lab. The shortened enrichment times and the innovative multi-channel rotary cycler combined to yield results faster than other PCR methods.

Implementing this system in the lab has proven very beneficial to TRAC Microbiology as well as its clients. “The advanced technology and inherent accuracy of Assurance GDS complements TRAC’s position and reputation as an innovative leader in testing, research, auditing and consulting,” says Howard. “We have, of course, been able to improve our service to existing clients and gain new clients based on our ability to confidently provide faster results.”

The ease and efficiency of the assay protocols has enabled TRAC Microbiology to substantially reduce the amount of hands-on labor and time required for pathogen testing, helping to greatly improve the company’s lab operations. The ability to obtain next-day results for both food and environmental samples offers tremendous value to food processors as well. These faster pathogen test results allow organizations to confidently release product sooner, maximizing shelf-life and reducing inventory holding costs. Additionally, faster results for environmental samples allow processors to identify and address potential problem areas in the plant sooner, reducing the quantity of product potentially exposed to a possible source of contamination.

www.biocontrolsys.com