It 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.
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.
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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