The Growing “Need for Speed” in Food Pathogen Testing

102050_AB Still C1091It seems every few months there’s another announcement about a new rapid method to test for pathogens. These developments have food manufacturers talking, but why the growing need for speed when it comes to food pathogen testing? And how do you know which method is right for you?

Faster answers, minimizing impact

The benefits of rapid testing are most obvious when you consider the investigation of a food-borne illness outbreak caused by a pathogen such as Listeria monocytogenes, E.coli  O157:H7 or Salmonella. These methods allow investigators to quickly link case strains and screen more samples. They also can accelerate root cause investigations so manufacturers can get to a resolution more quickly.

Rapid pathogen testing can also be extremely useful in preventing an outbreak of illness. Manufacturers can identify issues in a plant sooner and take marketplace actions more quickly. In some cases, these methods may even help manufacturers verify process controls and take action before a product is even made.

Overall, rapid diagnostics can reduce the impact of testing at food manufacturing facilities. These methods can lower the costs associated with “test and hold” programs, such as additional product handling and storage, missed or delayed shipments, retrieval of inadvertently released product that is being tested. This can reduce line delays and downtime, and the subsequent impact on “usable” product shelf life.

To specify, or not to specify…

That is the question for food manufacturers weighing the pros and cons of the two primary methods for rapid pathogen testing: immuno-assay and genetic-based.

Immuno-assay methods involve studying the proteins found on the surface of a cell. It’s a similar approach to, say, blood typing. However, because analysis is on the surface, you can get cross-reactions with closely related organisms. The results from immuno-assays are therefore presumptive and may require confirmation. However, this relatively simple method tends to be less costly, so if cross-reactions are not a concern, immuno-assays are a sufficient option.

The genetic-based method entails growing cells, breaking them open and looking at the genetic material within. If the genetic material contains elements specific to the organism you want to find, then it is amplified so it’s easy to detect. This considerably more complex method requires additional equipment and technical requirements, leading to higher costs. Yet the reduction – or even elimination – of cross reactivity, leads to more definitive results.

No “ideal” method…yet

Although there are exciting developments in assay automation on the horizon, bringing with them greater efficiencies (and likely costs), the “ideal” rapid method is yet to be revealed.

Until then, most labs today recommend genetic-based methods for their increased sensitivity, specificity and lack of cross-reactivity issues.

For those considering rapid testing, weigh the trade-offs of cost and complexity with your needs and the lab’s capabilities. Each situation poses its own unique requirements. And when looking for a testing partner, talk to your vendors, internal and external labs, and your trusted network of peers. There’s no faster way to find the solution that’s right for you.

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About Joe Meyer

In October 2010, Joe Meyer joined the Nutritional Chemistry and Food Safety business unit within Covance as Director of Microbiology. Joe is responsible for providing scientific and technical leadership in the areas of food microbiology and food safety for Covance. He helps ensure that the food testing laboratories are harmonized in their scientific and technical approach to testing and helps identify opportunities for Nutritional Chemistry and Food Safety to expand their capabilities. Joe has over 20 years of food industry experience. He worked for Kellogg, ConAgra Foods and Kraft Foods prior to joining Covance. Much of his career has been spent on the control of foodborne pathogens in the manufacturing plant environment, rapid methods for identification and genetic characterization foodborne pathogens, and continuous improvement of food safety systems such as Hazard Analysis Critical Control Point (HACCP). He’s also had experience in quality management and scientific and regulatory affairs. Joe continues to be involved with several trade association committees and advisory boards. Joe earned a Bachelor of Science degree in bacteriology from the University of Wisconsin in Madison, WI, and is a member of the International Association for Food Protection, the American Society for Microbiology, the Institute of Food Technologists, and the American Public Health Association.