Listeria: Is Ignorance Bliss?

Here is my fundamental thesis statement: it’s better to have less/fewer Listeria than more. 

How controversial can this be!? We will see at the FDA public meeting Aug 18 and 19. FDA has several key questions they are asking participants to opine on (note: comments are open until Nov 2)  

This is not a post about encouraging testing zone 1 food contact surfaces, or the stories we tell ourselves about swabbing after sanitation instead of during production. This is a post that challenges people to think about risks and rewards. This perspective applies to foods that do not support the growth of Listeria monocytogenes and within the context of a robust environmental monitoring and corrective action system. The goal is not to normalize contamination, but to detect it earlier, respond faster, and reduce its presence over time. 

Outbreaks and recalls associated with Listeria monocytogenes clearly demonstrate that today, L. monocytogenes IS getting out in the marketplace. We all know the reasons why -generally poor hygienic design of equipment and/or facility issues combined with inadequate sanitation and the fear of regulatory or customer consequences associated with finding it. (Note: FDA’s first question starts “With the recommended measures from the 2017 draft guidance as a baseline, what additional… practices would be effective…” I don’t see anything close to full adoption of the 2017 draft guidance recommendations. We should be asking why). 

If our choice today is to: 

a) Knowingly allow food to infrequently enter commerce with low levels of Listeria spp. (NOT necessarily mono) (important qualifier- assume the food does not support bacterial growth), or 

b) Unknowingly allow food to frequently enter commerce with high levels of Listeria spp. (still not necessarily mono, and still a food that doesn’t support growth) 

Which would you choose? Obviously choice C, food with no Listeria spp. (and certainly not mono) is the best choice. But it’s not realistic. 

Today, we as a broad food community are choosing Option B. And this is why we continue to have outbreaks and recalls. This is why the incidence of listeriosis is stagnant.  

Choosing Option A takes guts that many don’t have. Again, Option A comes with serious guardrails—limited foods (those that do not support Listeria growth), with “infrequent” and “low levels” unambiguously defined. But, with Option A, you know that some amount of Listeria spp. is in the product. Even if the “low levels” are less than the commonly cited 100 cfu/g (and that IS for mono, not spp.), the idea of letting this product go makes people extremely uncomfortable.  To be clear, this is not acceptance; its controlled visibility, linked with action. FDA calls out RTE foods that don’t support growth in question 3c. How can those manufacturers prevent contamination of their foods? Permit, no encourage, them to really look for it by reducing the penalty associated with an occasional finding. 

Here’s why I like Option A: With Listeria spp., you’re casting a wider net than with mono, meaning that you’ll hit the thresholds of ‘infrequent’ and ‘low level’ more often by looking for spp. than mono. This should be protective. Just as importantly, because you know something was there, you can hunt it down, eradicating the source.  

I don’t love the term ‘ubiquitous’, but because Listeria (spp., including mono) are out and about- in dirt, on shoes, on incoming raw materials, etc., finding an occasional positive is not the end of the world. Personally, when someone tells me they’ve never had a Listeria spp. positive in their EMP program, I’m immediately skeptical of their plan. The mere presence of Listeria spp. -in a production plant or the resulting food- is not evidence of insanitary or unhygienic conditions, and it’s not a public health threat. Still, the stigma around Listeria, even spp., is strong. 

If you’re thinking, ‘But why not just throw the lot away? Why take the chance?” It brings us back to where we are today. It makes finding a positive, the end of the world. If a low level of Listeria spp. in a food that does not support bacterial growth is cause for disposition, why would anyone even look? The status quo is not risk management, its risk avoidance through reduced or zero visibility, which makes none of the food safer. It makes problems harder to find, until a bigger issue arises, i.e., illnesses and recalls. That’s option B. Bliss.