Tag Archives: Listeria

By Bob Lijana

Over the past six months we have shared a series of articles on many practical aspects of managing Listeria. A summary of each of these articles follows immediately below after their respective titles. In addition, we have added a list of additional references on this subject. Links to all the articles in the series are in the Related Articles section below

What is Listeria: Listeria monocytogenes is one of the most virulent food-borne pathogens. It is an extremely strong organism, able to survive a wide pH range and a wide temperature range. These survival characteristics make Listeria a very insidious organism. Just because a food is cooked or has preservatives or has a low pH doesn’t mean that Listeria is not present—it’s quite the tough organism. Assume it’s there.

Listeria-Related Regulations (FDA & USDA): FDA and USDA have an essentially “zero tolerance” policy for Listeria monocytogenes in foods. However, in spite of past mistakes and costly recalls, Listeria-related recalls still occur. All regulations preach an ongoing vigilance to Listeria presence in the plant environment and in the food. Regulators also use DNA testing to find root sources of Listeria, which can prevent untold tragedy. Regulations help protect public health, so they should be used to that end.

Where Listeria Comes From, and How It Moves Around: Listeria is widely distributed in nature, found in soil, water, vegetation, and animal feces. Thus, it is quite easy for it to get into food plants and be transported around that plant. Given this, a wise food safety team always assumes that the organism is present somewhere in the plant. Harborages are all areas in which Listeria can grow; movement vectors are where those harborages intersect with people and equipment moving around. Best practices necessitate that harborages are eliminated and movement vectors are identified and controlled.

How to Find Listeria in the Plant: before you sample for Listeria, make sure senior management across all functions is supportive of this task, and is willing to share the risk of actually finding Listeria. Some companies test for Listeria species, and some test for a marker organism to avoid a zero-tolerance panic. Best practice is to establish, validate, and execute an environmental monitoring program which is based on strategic sampling of sites around the plant. Doing so is hard work, and requires a lot of patience since Listeria is notoriously hard to find.

How to Get Rid of Listeria in the Plant: there are two complementary approaches to managing Listeria: keep it out to begin with, and eradicate it when it is found. Keeping it out is hard, but try anyway—use interventions such as clean uniforms, captive footwear, and sanitizing mats prior to entry into production. And killing it—involve a reputable chemical company who understands food production. Use quaternary ammonium compounds judiciously, strategically, and smartly. Remember, you are rarely ever done!

Communication—The “Choice to Chase”: deciding to “chase” Listeria is a cross-functional decision, residing not only with the Food Safety & Quality Assurance team. Everyone buys in to be educated on actions and consequences, and to share the risk. The overall food safety culture needs to be one of honesty and openness in communication. A culture of support across the board matters significantly to making sure Listeria is managed well. This is also the kind of environment that FSQA professionals can be proud of, knowing they are making a very positive impact on public health and trust.

REFERENCES

Butts, J. 2003. Seek & Destroy: Identifying and Controlling Listeria monocytogenes Growth Niches. Food Safety Magazine. 9 (2). Available at: https://www.food-safety.com/articles/4802-seek-destroy-identifying-and-controlling-listeria-monocytogenes-growth-niches.
CDC. 2016. Etymologia: Listeria. 22(4). Available at: https://wwwnc.cdc.gov/eid/article/22/4/ET-2204_article.
Neogen Corporation and Cornell University. 2025. Environmental Monitoring Handbook for the Food and Beverage Industries, 2nd Edition. Available at: https://www.neogen.com/en/usac/neocenter/resources/food-beverage-environmental-monitoring-handbook/.
2008. Compliance Policy Guide CPG Sec 555.320 Listeria monocytogenes. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/cpg-sec-555320-listeria-monocytogenes.
2017. Draft Guidance for Industry: Control of Listeria monocytogenes in Ready-to-Eat Foods: Guidance for Industry. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/draft-guidance-industry-control-listeria-monocytogenes-ready-eat-foods.
2020. Get the Facts About Listeria. Available at: https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-listeria
2022. BAM Chapter 10: Detection of Listeria Monocytogenes in Foods. Available at: https://www.fda.gov/media/157717/download.
Foundation for Meat & Poultry Research & Education. 2021. Food Safety Equipment Design Principles. Available at: https://www.meatinstitute.org/sites/default/files/original%20documents/Sanitation%20booklet%202021.pdf.
Jay, J., Loessner, M., and Golden, D. 2005. Modern Food Microbiology. Available at: https://link.springer.com/book/10.1007/b100840.
Jespersen, L., Butts, J., Holler, G., Taylor, J., Harlan, D., Griffiths, M., and Wallace, C. 2019. The Impact of Maturing Food Safety Culture and a Pathway to Economic Gain. Food Control. 98:367-379. Available at: https://www.sciencedirect.com/science/article/abs/pii/S0956713518305863.
Lijana, B. 2021. Whole-Genome Sequencing: A Double-Edged Sword for the Food Industry. Food Quality & Safety. Available at: https://www.foodqualityandsafety.com/article/opinion-whole-genome-sequencing-is-a-double-edged-sword-for-the-food-industry/
Lijana, B. 2024. Checklists: Useful Tools or Traps? Food Safety Tech. Available at: https://foodsafetytech.com/feature_article/checklists-useful-tools-or-traps/
National Fisheries Institute. 2019. Ready-to-Eat Seafood Pathogen Control Guidance Manual. Available at: https://aboutseafood.com/wp-content/uploads/2018/09/3rd-Edition-RTE-Manual-Final-3-15-19.pdf.
Powitz, R., Balsamo, J., Coleman, N., Collins, C., Noonan, G., Radke, V., and Treser, C. 2025. Complexities and Strategies for Controlling Contamination. Environmental Health. 87(6):32. Available at: https://www.researchgate.net/publication/390360674_Complexities_and_Strategies_for_Controlling_Contamination.
SQF Institute. 2020. Food Safety Code: Food Manufacturing. Edition 9. Available at: https://www.sqfi.com/docs/sqfilibraries/code-documents/edition-9/code-pdfs/20227fmin_foodmanufacturing_v3-2-final-w-links.pdf?sfvrsn=7f70c75a_8
FSIS Compliance Guideline: Controlling Listeria monocytogenes in Post-lethality Exposed Ready-to-Eat Meat and Poultry Products. Available at: https://www.fsis.usda.gov/sites/default/files/import/Controlling-Lm-RTE-Guideline.pdf.
Zoellner, C., Ceres, K., Ghezzi-Kopel, K., Wiedmann, M., and Ivanek, R. 2018. Design Elements of Listeria Environmental Monitoring Programs in Food Processing Facilities. Comprehensive Reviews in Food Science and Food Safety. 17: 1156-1171. Available at: https://pubmed.ncbi.nlm.nih.gov/33350161/.

November 6, 2025

Beltway Beat

FDA Updates its Outbreak Investigation of Listeria monocytogenes: Prepared Pasta Meals

By Food Safety Tech Staff

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According to the FDA’s website, on September 30, 2025, the supplier of the affected pasta, Nate’s Fine Foods, Inc., expanded their recall of certain lots of pre-cooked pasta including fettucine, linguine, and farfalle (bowtie), after a sample of linguine pasta collected and tested by FreshRealm tested positive for Listeria monocytogenes.

On October 30, FDA updated the outbreak investigation stating the FDA, U.S. Department of Agriculture Food Safety and Inspection Service (USDA FSIS), and Centers for Disease Control and Prevention (CDC), in collaboration with state and local partners, are investigating illnesses in a multistate outbreak of Listeria monocytogenes infections linked to prepared meals.

Since the last CDC case count update on September 25, 2025, a total of 7 new illnesses from 3 states have been reported, with 2 additional deaths reported.  A total of 27 people infected with the outbreak strain of Listeria have been reported from 18 states. Of the 26 people with information available, 25 have been hospitalized and 6 deaths have been reported. One pregnancy-associated illness resulted in a fetal loss.

CDC and states are working to get information on whether sick people ate recalled food or if additional foods may be contaminated with Listeria monocytogenes.

FDA will continue to collaborate with federal and local partners and implicated firms and will provide updates as they become available.

October 16, 2025

Food Safety Hazards Conference

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This conference will focus on the detection, mitigation, control and regulations of food safety hazards through technology, best practices and data analytics. The Hazards include Listeria, e-Coli, Salmonella, Allergens, Chemicals and Foreign Matter. The conference scope includes both human and pet foods.

Food Safety Tech invites you to submit abstracts for consideration for the 2026 Food Safety Hazards Conference, April 20-22, 2026 in St. Louis, MO. Abstract Submission Deadline is Friday, December 12, 2025. The link connects you to the Abstract Submission Form

August 22, 2025

Beltway Beat

FSIS to take over inspections when Boar’s Head plant reopens

By Food Safety Tech Staff

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The Associated Press reported that Jarratt, Virginia, factory is set to resume operations in the coming months. It will face at least 90 days of heightened monitoring and inspections by federal Food Safety and Inspection Service officials. Previously, inspections were conducted by state officials who operated on behalf of the agency.

The Jarratt, Virginia, factory is set to resume operations in the coming months. It will face at least 90 days of heightened monitoring and inspections by federal Food Safety and Inspection Service officials. Previously, inspections were conducted by state officials who operated on behalf of the agency.

The change aims to “ensure the establishment consistently and effectively implements its corrected food safety plans,” USDA officials said in a statement. It calls for stricter enforcement if lapses occur.

The shift to direct federal oversight underscores the severity of the problems at the Boar’s Head plant, said Sandra Eskin, a former USDA official who now heads STOP Foodborne Illness, a consumer advocacy group. It raises concerns about communication between state and federal officials when problems occur, she added.

“Given its history, it’s particularly important that there be robust oversight of that plant,” Eskin said.

AP reported that Boar’s Head officials said in a statement that they have worked with state and federal regulators “to ensure the successful and safe reopening of the Jarratt facility.”

July 24, 2025

Beltway Beat

Update on Outbreak Investigation of Listeria monocytogenes: Ready-to-Eat Foods

By Food Safety Tech Staff

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The FDA and CDC, in collaboration with state and local partners, announced in a press release that they investigated illnesses in a multistate outbreak of Listeria monocytogenes infections linked to recalled Ready-to-Eat (RTE) foods, or products that do not need additional cooking, produced by Fresh & Ready Foods, LLC of San Fernando, CA.

The recalled products were identified by the “Use By” dates from 4/22/2025 to 5/19/2025 and include the following brand names:

Fresh & Ready Foods
City Point Market Fresh Food to Go
Fresh Take Crave Away

These products are no longer available for sale in stores.

CDC announced that the outbreak is over. CDC reports a total of 10 illnesses in two states. There has been a total of 10 hospitalizations and one death attributed to listeriosis.

FDA is working with Fresh & Ready Foods on corrective and preventive actions.

FDA’s outbreak investigation is complete.

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July 14, 2025

Ask The Expert

Where Listeria Comes From, and How it Moves Around

By Bob Lijana

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Listeria is widely distributed in nature, found in soil, water, vegetation, and animal feces. And since it can be found in soil, it has the ability to contaminate vegetables and produce grown in that soil. This can also occur if contaminated manure is used as fertilizer.

Thus, it is quite easy for Listeria to get into a food plant on someone’s shoes, or equipment being brought in from outside, or ingredients coming from a supplier.

Given the ubiquity of Listeria, a good food safety team (and their management) always assumes that the organism is present somewhere in the plant. Even with regular microbiological sampling coming up negative (i.e., no Listeria found), that is not a reason to lower the level of vigilance. Ever.

The insidious nature of Listeria is such that it can hide, even in untoward conditions, and it can be moved around, up, down, and sideways. The same factors which allow Listeria to enter a plant allow it to be transported within that plant.

Let’s talk about “harborages” and “movement vectors.”

Harborages are all areas in a plant which have the necessary conditions for Listeria to grow. Biofilms (resistant coatings which protect the organism) can offer an additional level of security for the organism. Listeria may or may not grow, but it can certainly survive. These areas (e.g., underneath equipment, in drains) are also called “growth niches” in the scientific literature.

Movement vectors are those locations in which harborages intersect with people and equipment moving around the plant. These are the opportunities for Listeria to move. These points (e.g., a fork truck running through contaminated water) are also called “transfer points” in the scientific literature. An example:

An employee accidentally drops Listeria-laden potatoes on the floor.
The employee walks through those potatoes and across another production line to get a stainless steel scoop to clean up the potatoes.
The employee walks back through the clean production line to scoop up the dirty potatoes, throw them in a trash container, and then put the scoop back.
Another employee, not observing any of this, picks up that scoop later to sample ready to eat potato salad.

As you can infer, unbeknownst to the employees, the potatoes were harborages for Listeria, and the scoop (and footwear) were movement vectors likely resulting in Listeria getting into food.

Now think about all of the movement and travel of people and equipment that occurs in your own plant. You may even see the following:

Fork trucks moving pallets from a warehouse to a product zone.
Stainless steel carts wheeled from one line to another.
Production operators carrying ingredients from one line to another.
Maintenance tool boxes being set on the floor, and then carried to another location.
Mixing implements being used and then hung for ready use later without being cleaned.
Bowls containing work-in-progress being wheeled across production lines on their way to a cooler.
Employees leaving their production line to get to a break area by walking across other production lines that use different allergens than theirs.

Best practices for Listeria control necessitate that harborages are eliminated and movement vectors are identified and controlled. Attacking Listeria in this way can reduce food safety risk dramatically. Note that the root source is almost assuredly a harborage site (a hiding spot for Listeria). So one of the best ways to find that harborage site is by identifying and mapping movement in the plant. Then follow the movement backwards and forwards, and up and down. You may find yourself surprised at where water can run or come from. And therein lie the “eureka” moments.

The objective is to identify the true root source of the Listeria, and eliminate it. This is very different than simply finding some Listeria and tossing sanitizer on it—this is very common, and people are lulled into believing that the Listeria has now been controlled. This is hardly ever the case if the root source has not been eliminated and if the movement vectors have not been identified and actively managed.

See the Related Articles below to read the series.

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July 12, 2025

Ask The Expert

Listeria-related Regulations, FDA & USDA

By Bob Lijana

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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.

See the Related Articles below to read the series.

To sign up for a free subscription to Food Safety Tech’s weekly Newsletter, click here

July 3, 2025

Ask The Expert

Listeria – From the Ground Up. How to Identify, Find, and Eradicate the Bugger

By Bob Lijana

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Over the coming weeks, we will share a series of six brief articles on Listeria. They are intended for food science professionals, especially food safety and quality assurance people. The information presented in these mini-articles will also be of interest to people in all functions. To that end, we have kept the language as non-technical as possible.

On roughly a biweekly basis, we will present mini-articles starting with what Listeria is, and the regulatory governance of Listeria in food from FDA and USDA. We will share background on where the organism comes from, how it can move around a food plant, and how to find it. We will share techniques on how to eradicate the pathogen. We will also share some insights on how to communicate learnings and successes, including with senior management. There will be references for further study.

Some of the information will already be known by those who have had to fight Listeria for many years, as is usually the case when this pathogen becomes your enemy. Yet that same information will be new and useful to those for whom the fight is new. These are people who are new to food manufacturing, or for whom a job in food safety and quality assurance is new.

Hence, pick and choose articles of most use to your situation as the series moves along. Yet do look at each one with a fresh pair of eyes–all of us could use a refresher in how best to manage the risk of Listeria in a plant, regardless of experience level. All plants and situations are different, so there is no “cookie-cutter” solution. If there were, we wouldn’t keep seeing recalls due to possible Listeria contamination. And we wouldn’t keep repeating history in that regard. We need to avoid complacence.

The ultimate objectives of this series are to provide suggestions of what can be done to manage food safety risks in a plant, and, at the same time, increase the company’s capability at providing safe food products and protecting public health.

See the Related Articles below to read the series.

To sign up for a free subscription to Food Safety Tech’s weekly Newsletter, click here

June 18, 2025

Beltway Beat

FDA, USDA FSIS, CDC and States Collaborate on Outbreak Investigation of Listeria from Chicken Fettuccine Alfredo Meals

By Food Safety Tech Staff

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The U.S. Food & Drug Administration (FDA), U.S. Department of Agriculture Food Safety and Inspection Service (USDA FSIS), and Centers for Disease Control and Prevention (CDC), in collaboration with state and local partners, are investigating illnesses in a multistate outbreak of Listeria monocytogenes infections linked to chicken fettuccine alfredo meals. Recalled product assembled at FreshRealm, Inc.’s San Clemente, California; Montezuma, Georgia; and Indianapolis, Indiana, manufacturing locations may be adulterated with the outbreak strain of Listeria monocytogenes.

As of June 18, 2025, a total of 17 cases have been reported from 13 states. Of the 11 people interviewed, 7 reported eating precooked meals, and 4 (57%) specifically reported eating chicken fettuccine alfredo. Of 17 people with information, 16 (94%) were hospitalized and there are 3 deaths attributed to listeriosis. There is one pregnancy associated illness in a mother that resulted in a fetal loss.

FDA has conducted a thorough investigation in response to this outbreak, including traceback of FDA-regulated ingredients within the assembled product. FDA used specific meal information reported by ill people, and collected by state officials and CDC, and firm records to trace FDA-regulated ingredients through the supply chain to the establishments where those were produced. FSIS identified the outbreak strain in a routine sample of FreshRealm’s chicken fettuccine alfredo collected on March 19, 2025. This lot of product was not distributed into the food supply. FSIS also used purchase documentation to trace chicken fettuccine alfredo products purchased by two ill people to FreshRealm establishments. An additional two ill people verbally described chicken fettuccine alfredo products they purchased. FSIS identified products produced by FreshRealm that matched the descriptions during follow-up at the retail stores where they shopped.

FDA also initiated multiple inspections, including sample collection, at the manufacturers of some ingredients used to make the chicken fettuccine alfredo product.

Testing of the FDA-regulated ingredients collected to date is complete and the outbreak strain of Listeria was not found. FDA and FSIS have not yet determined a source of contamination for this product; however, both agencies are working closely with each other and CDC to continue to collect information to determine what additional steps are needed to protect public health.

On June 17, 2025, in response to this investigation, FreshRealm, Inc., recalled their pre-made chicken fettuccine alfredo products sold at Kroger and Walmart.

July 23, 2024

Listeria Outbreak Linked to Meats Sliced at Delis

By Food Safety Tech Staff

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The CDC website reported that there is a Listeria Outbreak Linked to Meats Sliced at Delis. Many people in this outbreak are reporting eating meats that they had sliced at deli counters. Investigators are collecting information to determine the specific products that may be contaminated. Products sold at the deli, especially those sliced or prepared at the deli, can be contaminated with Listeria. Listeria spreads easily among deli equipment, surfaces, hands and food.

As of July 19, 2024, a total of 28 people infected with the outbreak strain of Listeria have been reported from 12 states (see map). Sick people’s samples were collected from May 29, 2024, to July 5, 2024 (see timeline). Of 28 people with information available, all have been hospitalized. One person got sick during their pregnancy and remained pregnant after recovering. Two deaths have been reported, 1 in Illinois and 1 in New Jersey. The investigation is still active and there has been no recall.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. USDA-FSIS is working to identify the suppliers of deli meats, sliced at deli counters, purchased by people in this outbreak.

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