To enforce food safety regulations, FDA and USDA have a “zero tolerance” policy for Listeria monocytogenes (Lm) in certain foods. This means Lm must not be found in any 25-gram sample. According to FDA’s Compliance Policy Guide, legal action may be recommended if Lm is found in a ready-to-eat (RTE) food that allows Lm to grow. While the compliance guide is not legally binding, the finding of Lm in your facility could still lead to enforcement by FDA.

Do note that this is a regulatory policy. It does not mean that the typical healthy individual cannot tolerate Lm. Quite the contrary, as recognized by other countries (such as New Zealand, Canada, and the European Union), some foodstuffs are allowed up to 100 CFU/gm of Lm (although the EU tolerance is supposed to change to “not detectable in 25 gm” as of June 1, 2026). For some foods, Japan allows even higher levels. Because of these higher limits, some people believe that allowing some level of Lm in a food is a very practical approach.

That said, the USA does not. Any food company—big or small—can face public health warnings, safety alerts, product withdrawals, or recalls because of Lm. No one is exempt if something goes wrong with how food is handled or processed.

Unfortunately, even with past mistakes and costly recalls, Lm-related recalls still occur. Some recent examples:

• July 2025: recall of over 350,000 lb of turkey bacon (Kraft Heinz—Oscar Mayer).
• June 2025: recall of chicken alfredo meals; at least 16 people hospitalized; at least 2 deaths (FreshRealm–Kroger and Walmart).
• May 2025: recall of nearly 90 vending machine sandwiches and other products; at least 10 people hospitalized (Fresh & Ready Foods).
• Apr 2025: recall of nearly 2,000 cases of ready to eat celery sticks (Duda Farms).
• Feb 2025: recall of frozen supplement shakes; 12 deaths (Lyons Magnus–Sysco).
• Jan 2025: recall of 2,000,000 cases of doughnuts and pastries (FGF Brands–Dunkin).
• Oct 2024: recall of 12,000,000 lb of pre-cooked meat and poultry (Bruce Pack).
• Oct 2024: recall of 200 varieties of frozen waffles and pancakes (Treehouse Foods—Food Lion, Harris Teeter, Publix).
• Aug 2024: recall of 7,200,000 lb of sliced deli meats; 10 deaths (Boars Head).
• Feb 2024: recall of 50 different cheese products; 2 deaths (Rizo Lopez Foods—Albertson’s, Trader Joe’s).

Even if one disagrees with the scientific basis for a “zero-tolerance” approach, all regulations require an ongoing vigilance to Lm presence in the plant environment (and of course in the food). This includes non-regulatory food safety schemes such as SQF (Safe Quality Foods). The current SQF Code (which is being updated for 2026) includes a requirement for a risk-based environmental monitoring program for pathogen detection, sampling, and eradication. To help in this regard, both FDA (“draft guidance for industry”) and USDA (“compliance guideline”) have excellent technical guidance documents. These publicly-available resources cover the microbiological aspects of Lm, how to identify Lm, and how to assess risks in order to determine appropriate preventive and corrective actions.

Regulators also use DNA testing in their quest to find root sources of Lm. Whole genome sequencing (WGS) is like testing for one’s ancestry. Listeria samples can be categorized based on their genetic (DNA) makeup. With an extensive database (e.g., PulseNet) FDA may be able to link the DNA from a Lm environmental sample in a plant with the DNA from a blood sample from someone who has been hospitalized with listeriosis. If FDA can also determine that the food was purchased in the same state as the plant is located and/or that the hospitalized person said that they ate that specific food, then FDA can link everything together.

Food manufacturers need to be aware of how WGS can affect their operations. A publication on this topic provides useful perspective from FDA’s point of view and the manufacturer’s point of view. These do not always align.

Regulations help protect the public health. Use these regulations as guides to protect the food you make.

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