The results are in

by Lynn Petrak
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Rapid testing methods speed time to results while maintaining sensitivity and spurring mitigation.
Rapid testing methods speed time to results while delivering on industry's promise of quality and safety.

As costly recalls and public relations crises have shown – including the recent high-profile shutdown of Chipotle restaurants for one day – guesswork is not an option for providing safe food produced in a clean environment. While not the end-all-be-all in safety, testing of the production environment and of both raw and ready-to-eat products is an important tool in delivering on the promise of quality, wholesomeness and safety.

The meat and poultry industry presents its own set of challenges within the food chain when it comes to testing. “Meat and poultry are highly perishable and processors need to make rapid decisions on whether they are able to release product into commerce. Time is of the essence and companies need a method that will quickly tell them whether a pathogen is there, and they also need a method that is robust and will perform across challenging matrices efficiently,” points out Erin Dreyling, Ph.D., vice president, commercial support for Roka Bioscience, Inc., Warren, New Jersey.

Speed has taken on greater importance in recent years in an ever-competitive marketplace. “Rapid testing is the way of the world these days, to get the product out as fast as you possibly can and meet all the necessary requirements to make sure your product is as safe as it is high quality,” reports William “Bill” Hogan, president, CEO and director of FoodChek Systems, Inc., Calgary, Alberta, Canada.

“How rapid? That is the question. For Salmonella and E. coli O157:H7, the ideal is moving toward the same-shift assay, to get a presence/absence and results in eight hours,” says Mike Clark, international group product manager, PCR Food, Bio-Rad Laboratories in Hercules, California. “We’re aware of that demand and we are always pushing for faster time to results.”

Dreyling agrees: “What we’re seeing is everyone wants faster results.”

A pivotal concern, of course, is synching speed with accuracy. “When you start thinking about shortening enrichment times, the challenge is how to maintain the sensitivity of an assay. It’s key that companies are looking to methods that get them results, but maintain sensitivity,” Dreyling notes.

That point is underscored by Timothy Freier, Ph.D., division vice president, scientific affairs and microbiology for Mérieux NutriSciences, Chicago. “As pathogen detection technologies have moved from turnaround times of several days to 24 hours or even less, the importance of validating or verifying the test method has become even more important. These very rapid methods are typically running very close to the limits of detection, so even a slight interference from the sample matrix, an increase in the sample size or a change in the ratio of the sample to enrichment broth can lead to false negatives,” he says. “It is critical that an expert microbiologist considers all these variables and determines whether a method validation or a method verification should be conducted.”

In addition to validation and the need to maintain sensitivity, another issue is the internal buy-in needed to implement such systems. “There is a management change element to it – if you want to make the system faster, you have to look at changes in protocol and processes,” Hogan remarks, noting that faster tests necessitate an optimization of lines and testing processes. “The mantra is to deliver the highest quality and safest product. But you can also use it as a marketing tool.”

As testing and speed-to-results ramp up, experts are quick to note that testing is multidimensional in effect. “You can’t test your way to a safer product, but your test provides a lens into the level of risk in the product and to mitigation,” observes Ted Andrew, senior director, product marketing for Roka Bioscience. “Mitigation is what testing is supposed to drive – ‘I got a positive result, now what?’”

Hogan concurs. “With rapid testing, you find out sooner whether or not you have an issue,” he says.

Enrichment Class

Recent years have brought several advances in tools and technology to enable faster results, with improvements in different aspects of testing.

Food Chek Actero Listeria rapid testing kit
FoodChek's Acero Listeria enrichment media offers the ability to get results from testing in under a day.

For example, FoodChek offers the ability to get results from Listeria testing in under a day. “We’re working on things in our media to make results time even faster, and with that comes more optimization,” he remarks.

According to Hogan, customers can perform a single stage, 20- to 26-hour enrichment in FoodChek’s Actero Listeria enrichment media, followed by rapid real-time processing with the DuPont BAX System. Enriching food samples in Actero Listeria enrichment media allows laboratories to use about 33 percent less media per sample than other methods.

Meanwhile, experts at Roka Bioscience are likewise working to shorten the results window while maintaining sensitivity through the company’s fully automated Atlas pathogen detection system. “With our Atlas system, we’ve reduced time to result, depending on pathogens, from eight to 12 hours followed by three to five hours on the enrichment,” Dreyling reports.

Among other testing solutions, Bio-Rad offers an assay that provides results after a 24-hour enrichment. “That’s about as fast as what’s out there,” Clark notes.

Neogen Corporation, Lansing, Michigan, is also cutting down on results time with new rapid and accurate tests that use an isothermal reaction method to exponentially amplify the DNA of any target bacteria present in samples. “In the last few years, we’ve come out with a PCR machine, the ANSR, that doesn’t require a thermal cycler,” says Joe Heinzelmann, market development manager, adding some of the E. coli tests are 10 hours, while some Salmonella tests are as short as 16 hours. “There is a 10-minute reaction time for Salmonella and E. coli after enrichment. And all of that application happens at one temperature and in real time.” Neogen’s ANSR for Listeria, meantime, provides genetic level discrimination of specified targets in 18 minutes post-enrichment.

Other technologies are pushing the testing envelope, too. A growing area in both interest and capability relates to Salmonella limits testing. Roka Bioscience has focused some of its efforts on Salmonella limits testing that allows processors to identify points in their production chain impacted by Salmonella. “This is a new way for poultry manufacturers, from production all the way through, to look at the process and try to meet new regulations by thinking holistically,” Andrew explains.

Mérieux NutriSciences has also deployed Salmonella limits testing as a method for rapid testing in raw meat and poultry. “This is a technique that is semi-quantitative, meaning it falls somewhere between the typical positive/negative enrichment assay and a fully quantitative assay such as direct plating or ‘Most Probably Number’ testing,” Freier explains, adding that limits testing is being used to differentiate – typically within eight hours – between normal lots with low levels of Salmonella and more highly contaminated lots more likely to cause illness if mishandled or undercooked.

Another area benefitting from new technology is related to genomics. Neogen offers a Salmonella serotyping service that provides molecular serotype determination from a colony isolate in 72 hours, according to Heinzelmann. The assay utilizes targeted amplicon PCR combined with next-generation sequencing to develop a genetic profile for the colony isolate and then compares those sequence results with the known genetic makeup of the reference database to determine the specific Salmonella serotype present. “Now, instead of using a whole genome sequence, this is more cost effective. At $99 a sample, they can do a serotype test on performance positives,” explains Heinzelmann, who notes that the serotyping service can be used in environmental testing, too.

Bio-Rad is also looking at the future and acting accordingly. Recently, Bio-Rad joined the Consortium for Sequencing the Food Supply Chain established in 2015 by scientists from IBM Research and Mars, Incorporated. The consortium is combining advanced genomics with new informatics tools to observe microbial communities in food and detect hazards in the food supply chain that can threaten safety; Bio-Rad will contribute its expertise in chromogenic and molecular food tests for food pathogens and food quality indicators.

Testing of the production environment, raw and ready-to-eat producgs is an important tool.
A growing trend is to outsource testing to a contract laboratory.

Scratching the Surface

To that point, in addition to product testing, environmental testing is key in tracking and addressing food safety issues. “In the last two or three years, there has been a high level of engagement for environmental testing,” Dreyling says, adding that outbreaks linked to Listeria and Rubella sparked some of that interest, as well as new regulations that are part of the Food Safety Modernization Act (FSMA).

Roka has added to its Listeria environmental detection assay, Dreyling says. “It’s specifically designed to address the unique challenges that come with environmental samples – it’s highly sensitive and also user friendly with a rapid time to result,” she says, adding that the total time is 27.5 hours.

All in Good Time

Beyond cutting-edge capabilities, getting faster results can be a matter of logistics. “Every increase in turnaround time for pathogen testing is not necessarily linked to advanced molecular technologies,” Andrew points out. “Sometimes it is as simple as getting the samples to the lab quicker.”

To expedite results, some processors are enlisting help. “One growing trend is to outsource testing to a contract laboratory that has a satellite laboratory located on the same property as the manufacturing facility. This gives the advantages of using a third-party lab while avoiding the delays of packaging and shipping samples,” Freier notes. Another related trend, he says, is the use of creative courier services that can get samples to the lab quicker than the use of commercial overnight shipping services.

Working with third-party or outside labs can be a solution for smaller processors, Dreyling notes. “We also work with a lot of third-party testing labs, and are able to give small and mid-sized processors access to state-of-the-art technology that way,” she says, adding that processors have a lot of options, from using tools placed in the plant, in a plant’s lab, or in a third-party lab.

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