Any food safety professional would agree that it is not reasonably possible to test all risk out of a food production system. While we can sample incoming ingredients, the production environment, the employees (i.e., gloves and smocks), the utensils, the production lines, and the finished product, even with the most robust testing program, microscopic pathogens can still evade detection.

So, on the spectrum of testing robustness, many companies ask themselves a few basic, but also critical, questions. First, when should we be testing? Second, where should we be testing? Third, how frequently should we be testing?Fourth, what should we be testing for? And, fifth, should we use any kind of strain typing technologies if, and when, we do find positives?

The first question is the most simple to answer. Companies should be testing their environments at least 3-4 hours into production. This is the best (and, frankly, only) way to ensure that if pathogens are residing in the production environment, they will be found. Testing sanitized stainless steel is utterly useless if a company is truly really aiming to find pathogens residing in the environment.

With respect to the question of “where” companies should be testing, I often recommend engaging in what I call smart sampling. While using a random site generator can ensure non-biased coverage over large areas, it’s important to consider whether the randomness might backfire by diverting important testing resources away from those areas that might be more likely to harbor bacteria. Thus, I often urge companies to consider sampling in those areas that: (1) are more difficult to clean, sanitize, and control; and (2) best suited to protect Zone 1 surfaces and finished product (i.e., sampling more aggressively with available resources in Zone 2 areas, and less aggressively in Zone 4 areas).

Where not mandated by USDA, testing frequency is also an area that can get companies into trouble. Collecting 20 samples every quarter from each line is likely useless, while collecting and testing 20 samples from each line per week is likely to provide more useful data. I am a firm believer that, when it comes to sampling generally, robustness is the key to success. It also mitigates the chances that USDA or FDA would find significant environmental contamination if they conducted a Food Safety Assessment (USDA) or a routine swab-a-thon (FDA) — because any existing contamination would already have been identified and removed.

When it comes to “what” companies should be testing for, it obviously depends upon the risk profile of the incoming ingredients, facility, and product. When defending against Listeria intrusion, for example, I recommend testing for species, and then confirming each positive for Listeria monocytogenes. That way, if the pathogenic strain is identified, it will provide the company with additional incentive to take appropriate action to find the root source of the contamination, and then eliminate it altogether.

Finally, many companies are now asking, “Should we be using strain typing when we have a positive?” My answer to that question is almost always “Yes, you should.” Ribotyping and WGS have proven to be effective tools for food companies looking to win the War on Pathogens within their facilities. Typically, we facilitate typing by setting up a seperate account with our chosen lab for the purpose of typing, and listing our firm as the “report to.” So long as strain typing is not part of your written food safety program, our position has always been that the information remains confidential to the company, and does not need to be shared with regulators.

In any event, as companies think about the level and types of testing they want to add to their arsenal, it is always important to choose the methodology and system that will yield the most helpful results. In many aspects of life, “less is more.” When it comes to testing, however, “less” will likely translate to a “loss.” Thus, don’t be shy about testing your tolerance for testing, and picking the path that will be the best suited to ensure a cleaner environment, and a safer finished product.

Testing your tolerance for testing

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