Rapid Testing Methods—The Future

Welcome to Part 3 of our three-part series on the use of rapid microbiological methods (RMM) in food safety testing, where we continue to present what we learned from our survey of more than 250 food processors from around the world, conducted in late 2023. If you missed Parts 1 and 2, they can be read here ¹ and here.²

As we mentioned in Part 1, there has been substantial growth in the development and use of rapid methods since their introduction to the market over the past 25 years or so. When these methods were first introduced, they were originally intended for use by food processors in their in-plant laboratories. Over the past decade, with the increase in outsourcing due to concerns for cross-contamination from pathogen samples, fewer and fewer food companies have an in-house microbiology lab. (As mentioned in Part 1, 78 percent of the companies in our survey reported that they no longer have an in-house microbiology lab.)¹

Laboratory Outsourcing

Food safety and concern about cross-contamination are the major reasons companies outsource tests, especially pathogen analysis, to commercial labs. In the current survey (Figure 1), this issue does not show up as dramatically as one might expect as a "primary reason" because—and this is clear from the comments we heard—the risk is so commonly recognized that the need to outsource is taken for granted, and it is largely no longer a "decision" to be made. This effect may be seen in the result that roughly one-third of the survey respondents reported their "laboratory capabilities" as another significant reason for outsourcing. Most companies are saying that they no longer have a microbiology lab, or, if they do, it does not have capabilities for pathogen analysis since these tests are outsourced. This concern for safety is indeed paramount, and these two responses are largely due to this same driver.

FIGURE 1. What Are the Main Reasons That You Outsource Microbiology Tests?

Other drivers of outsourcing include client requirements and the need for validation, with these two reasons also often being one and the same as more customers are requiring data from only ISO 17025 accredited labs. People also report outsourcing for confirmation of their own tests and for more sophisticated tests, such as sequencing and other identification tests.

This trend changes the types of RMM that will be in demand in the future, and will split the market into in-plant tests and those being employed by commercial laboratories. Those who use RMM for in-plant applications will look for tests that are fast but also easy to use, as they will be used by plant employees and not lab technologists. Meanwhile, those tests destined for use in commercial labs will also need to be fast, but with a focus on higher throughput and efficiency and with an eye toward operational efficiency and profitability for the lab.

How Fast is Fast?

So how fast do RMM need to be? And, is faster even better? Can even faster tests provide even better operational benefits, or have we reached some level of diminishing returns where faster provides only marginal improvements?

It seems that it depends on what you do and your particular processing situation.

In general, most of the companies in our survey indicated that tests with a turnaround time of less than 24 hours would be "useful," and tests with an 8 hour or less turnaround time would be a "nice to have." Very few respondents indicated that a test with a turnaround time of less than 8 hours was necessary.

As might be expected, many said that a faster test would allow for faster decision-making. As one quality assurance (QA) manager at a processed food company mentioned, "…faster results give us more time to react and investigate when we get a positive pathogen result." Another QA manager at a dairy company pointed out, "…shorter turnaround times help us to take immediate action, and the amount of affected product that needs to be isolated is smaller."

These comments should not be surprising, as these are some of the key benefits of rapid tests. However, many respondents also pointed out that faster tests are only useful if companies have the capacity to make use of the information. Consider the use of a test that requires a 24-hr turnaround time. A lab analyst can start the test at 9:00 a.m. one morning and get the results back at 9:00 a.m. the following morning, at the beginning of the next day's shift. Now imagine that a new technology becomes available with a 16-hr turnaround time. This is a significant time reduction, but if no one is in the lab to read the test overnight, then there is no useful benefit. So, the faster speed is only useful if it meets the schedule and the specific needs of the business.

Faster tests can also get out of sync with the operational demands of a plant, not only from a timing perspective, but also from a capacity standpoint. As the QA manager of one poultry company mentioned, "If the tests get too fast, our lab will not be able to keep up with the demand for lab analysis and reporting." As with the timing example above, an analytical test with, for example, results available in 4 hours does not help much if no one is available to repeatedly receive and report those results. Any lack of lab personnel or distraction from other tasks that causes a delay in reporting results also negates the improvement in speed from the test itself. Imagine the backup that could be possible from a series of tests with a 1-hour turnaround time that would require constant analysis and reporting. For most companies, this would require additional dedicated personnel in an environment where their budgets are already stretched. So, this constraint may represent a considerable headwind for the utility of ever faster tests. To take advantage of faster turnaround time, the test must fit in with scheduling and available labor capacity, or offer benefits that are easily recognized to justify additional investment in personnel to make the benefits accessible.

What is Next?

Outsourcing has amplified the role of commercial labs, especially related to pathogens. This is also not going to change anytime soon (other than to increase globally), but it will more firmly entrench RMM technologies like PCR and ELISA in those commercial labs and drive more market maturity and competition for diagnostic companies that compete for that business volume. This will drive the development of new RMM product improvements that enhance the efficiencies of commercial lab analysis, such as higher sample throughput and lab automation.

For the other track of in-plant use, where food companies are still looking for better and faster information to drive operational decisions, the competitive front for RMM is likely moving to rapid tests that will be used by plant personnel primarily for environmental monitoring and product changeover decisions. These tests will need to be fast and easy to use, just like we heard in our survey results. What they may not need to be is highly accurate, at least not like the more definitive tests employed in a commercial lab.

Now, does this mean that food companies are looking for inaccurate tests? No, of course not. As we saw in Part 2 of this series, the third most desired feature of RMM is accreditation.² So, the tests will need to have proven credibility and accuracy. There is a difference, however, between the highly accurate reference tests used by commercial labs and those that are accurate enough to drive better decision-making. Molecular-based technologies, like PCR and WGS, can very accurately detect and identify pathogens to the serotype level or fully sequence their genome. These are very powerful technologies that have driven revolutionary changes in food safety. However, that level of accuracy and specificity often amounts to "swatting a fly with a sledgehammer" when it comes to the information needed to confirm that cleaning and sanitation processes have been performed correctly. Technologies that work more like an ATP test—or the rapid, easy-to-use indicator tests mentioned in Part 2—that can be employed by plant personnel and provide a positive/negative result within a few minutes and allow for better-informed plant-level decisions like, "Do we have to re-clean?" or "Are we OK, and is it time to go home?" will be in demand. These types of innovative "good enough" tests are likely to be the frontier for new technology development and growth for in-plant tests.

It is reasonable to expect that we will see different developments from these two tracks. Food companies working with their lab partners will need to decide on the right mix of both for the best food safety outcomes. Food Safety Insights will continue to keep an eye on all of these developments as they occur.