31 January

Controlling Listeria Monocytogenes in RTE Foods: FDA’s Draft Guidance Is Out And Its Making Waves

FDA recently released draft guidance (the “Guidance”) on controlling Listeria monocytogenes (LM) and ready-to-eat foods in conjunction with the final rule, Current Good Manufacturing Practice, Hazard Analysis, and Risk-Based Preventive Controls for Human Food (PCHF rule). Any FDA regulated facility that manufacturers, processes, pacts, or holds RTE foods needs to take the time to read this new draft Guidance. Why? For three reasons. First, as we all know draft guidance can often take years before it turns to final guidance and in the interim FDA inspectors still rely on it as gospel. Second, whether it’s considered draft or final by FDA we all know the reality is that guidance is often treated like directive, which in turn is often treated just like regulation. If we don’t follow it, we have a lot of explaining to do. Third, there are a few waves contained in this guidance that we as an industry all need to be aware of now!

Since the guidance is so closely aligned with the PCHF requirements and places. A notable expectation on conducting a hazard analysis and implementing risk-based preventive controls, including verification of preventive controls-- notably for the prevention of LM as this is the primary focus of the new guidance.

The guidance discusses issues that are not surprising, or wave making such as topics involving current good manufacturing practices such as controlling personnel; buildings and facilities; equipment and utensils; production and process controls; and warehousing and distribution against the risk for LM. What’s making more waves is the agency’s thinking regarding effective strategies for controlling L. monocytogenes in RTE foods, including identifying the risks associated with raw materials and ingredients, the use of listericidal process control, environmental monitoring, product testing, and the analysis of verification data trends.

Below is a summary of the key contents of the draft guidance:

Assessment of Ingredients and Raw Materials

According to the guidance, raw materials and other ingredients (raw or minimally processed) should be assessed to determine if it is “reasonably foreseeable” that the ingredients might be contaminated with L. monocytogenes. Based on the outcome you should establish a list of raw materials and other ingredients that may reasonably foreseeably be contaminated with LM. (An addendum to your hazard analysis, perhaps?) What ingredients are more susceptible to LM you ask? That is the benefit of conducting a risk-based, science-based hazard analysis under the PC HF rule, isn’t it? This said, the draft guidance calls out the fact that such ingredients are unlikely to be contaminated if the raw ingredients were subjected to a validated listericidal control measure, such as aseptic processing and packaging, pasteurization, retort processing (e.g. canning) or other approved in-package lethal technology (e.g. irradiation.)

The guidance recommends periodic testing of raw materials or other ingredients to verify your supply chain control program namely that your supplier has a validated process preventive control to adequately control the LM hazard of concern. In the agency cautions us not to rely on a supplier provided Certificate of Analysis alone showing negative test results for L. monocytogenes-- the guidance clearly recommends that companies periodically test raw materials/ingredients to verify the supplier’s control programs and to ensure that we contamination is not occurring prior to receipt. A word of caution though. Look at your receiving verification testing strategies because the guidance states, “testing a single lot of a food product for L. monocytogenes is of limited value.” Rather, the guidance recommends companies to test multiple lots of raw materials and other ingredients until enough experience and data is gathered to be confident in the results provided on the COA. Once confidence is built testing can scale back and continue on a less aggressive schedule, i.e. weekly, monthly or quarterly, based on risk.

RTE Foods
Certain types of foods supports the growth of L. monocytogenes. Fruits, vegetables, many types of cheeses like soft ripened cheese, fresh soft cheese (Queso Fresco), high-fat dairy products like ice cream and milk, soft unripened cheese, semi-soft cheese, soft-ripened cheese,)raw shellfish, deli meats, and more.

The guidance recommends RTE foods should be formulated, if possible, with intrinsic (physical or chemical) properties that inhibit the pathogen in order to control the growth. Examples include: pH less than or equal to 4.4; water activity less than or equal to 0.92; and the use of inhibitory substances or processes.

Listericidal process
The manufacturing process of certain RTE foods utilizes a listericidal process control that can consistently destroy the pathogen so it cannot be detected in the finished food product. The effectiveness of a listericidal process control should be demonstrated through scientific studies and include information from the scientific literature, modeling, and challenge studies, when needed. The guidance suggests a few different approaches for demonstrating the effectiveness of a process control, including reference to applicable scientific literature, published or internal validation studies, and the use of historically established process controls (e.g. milk pasteurization parameters).

Environmental monitoring
The draft guidance covers the goals of an environmental monitoring program, strategies for environmental monitoring, sampling areas/zones based on potential product contamination, and the need for scientifically valid, written procedures for environmental monitoring. This makes sense as we know LM is a significant pathogen of concern in many facilities that requires effective pathogen control programs, and the FSMA rule for preventive controls (21 CFR 117) identifies L. monocytogenes as an environmental pathogen, and a mandatory hazard evaluation, “must include an evaluation of environmental pathogens whenever an RTE food is exposed to the environment prior to packaging and the packaged food does not receive a treatment or otherwise include control measure” to significantly minimize the pathogen (21 CFR 117.130).

Where the new guidance starts to move away from prior practice and doctrine and from the FDA’s 2008 draft guidance regarding LM control is how facilities should react when they find Listeria in RTE food and/or processing environments. To some, this new policy comes as a surprise. To others, it comes at their request. Because it was stated by FDA that it was at the request of industry that the new guidance is modeled on the “seek and destroy” approach of USDA’s FSIS (Food Safety and Inspection Service) for RTE meat and poultry. In the new Guidance, FDA manufacturers/processors are encouraged to implement robust environmental sampling programs, and to promptly respond to positive test results using effective risk-based corrective actions.

For example, if LM is found on what is known as a zone 1, or food contact surface (FCS) the Guidance recommends that “you should either reprocess with a validated listericidal control measure, divert to a use in which the food will not be consumed by humans or animals, send for use in food to be consumed by animals where appropriate, or destroy that lot of RTE food, and consider whether there is product in commerce that should be recalled.” There is a table on page 50 of the draft Guidance that lays out the corrective actions with listeria is found in an environmental sample, and what a facility is expected to do if found on a food contact surface.

Sampling and Testing RTE Foods
The guidance recommends the sampling of food samples for the presence of L. monocytogenes, but thankfully this is still based on the notion of being risk-based, like the FSMA Preventive Controls rules based on criteria like customer requirements, the risk of foodborne illness if the finished product is contaminated with L. monocytogenes, and the frequency of detection of Listeria spp. in environmental samples.

Where we see the greatest change from prior expectations and practice is the expectation to speciate from Listeria spp to Listeria Monocytogenes if the product supports the growth of L monocytogenes. The Guidance suggests testing food products for L. monocytogenes rather than for Listeria spp. particularly where the product supports growth. According to the guidance, if testing for Listeria spp shows a positive result, then further testing is needed to determine if L. monocytogenes is present or if the food should be treated as contaminated.

Now do you feel some waves? (And if you read the 483 from a major ice cream recall it was only a matter of time before this was going to be an industry expectation in my opinion).

Trend Data
On balance industry can always improve when it comes to tracking and trending data. The draft Guidance recommends that verification data collected from environmental monitoring and product testing programs be analyzed to identify trends over time as it could uncover that LM. is not adequately being controlled within a production facility. Trend analyses could reveal an increased incidence or persistence and corrective actions could be taken early, before an actual contamination or worse, outbreak occurs that sickens or even causes the death to humans or animals.


Review your environmental monitoring and product testing programs, and determine how each may need to be revised in light of this new draft Guidance on Listeria Control for RTE Foods. The expectations are changing when it comes to Listeria control. Make sure you have updated your playbook!





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