Regulatory guidance for Listeria reflects healthy attitude shift

January 31, 2019

Research has made it clear in recent years that, above many other food safety practices, monitoring the food production environment in a “seek and destroy” approach is the best way to tackle Listeria contamination threats.

In fact, Food Safety Magazine found in a wide-reaching survey that environmental monitoring for Listeria is the “fastest growing category” of such monitoring. Of the 262 food processors surveyed, 35% reported that they planned to increase Listeria sampling by an average of 107%.

Regulatory guidance from agencies such as Health Canada and the U.S. Food and Drug Administration (FDA) states that the environment is the predominant source for Listeria contamination of food. Sites within a food production and handling facility that harbor the bacteria act as sources for continuous contamination. This undesirable situation is further magnified if the food product happens to support the growth of Listeria.

Product risk categories

In its document “Guidance for the Application of Health Canada’s Policy on Listeria monocytogenes in Ready-to-Eat Foods,” Health Canada identifies two risk categories for Listeria:

Category 1 RTE foods support the growth of Listeria monocytogenes (L. mono) at all points of their shelf lives, meaning they and their production environments are a high priority for Listeria monitoring and control. This category includes foods like cheeses, milk and any cultured dairy product, egg mixes, pasteurized liquid egg, cooked egg products, ready-to-eat meats (like deli meats and hot dogs), and fresh produce.

Two sub-categories comprise Category 2 RTE foods. Category 2A, the medium-to-low priority group, support limited growth of L. mono (specifically, no greater than 100 colony-forming units per gram) during their shelf lives. They may occasionally contain low levels of L. mono and don’t have a kill step (validation study required), and/or have a refrigerated shelf life equal to or less than five days (no validation study required). Category 2B products don’t support L. mono growth and are low-priority. Validation studies are required unless frozen or meeting specified physicochemical properties.


Among its suggested strategies for combating Listeria cross-contamination, Health Canada outlines two approaches: Proactive Activities, and Reactive Activities. Both are necessary, but if you implement the former consistently, you’ll have to rely less on the latter.

Proactive activities include all steps that can prevent Listeria contamination. Some of these may seem intuitive, like environmental and product sampling. Others offer less tangible but still critical benefits, like industry communication on issues related to Health Canada policies. This can cover everything from website postings to real-life conferences discussing important food safety topics.

Reactive activities are conducted in response to detection of Listeria in finished product or the production environment. They can include all of the above proactive activities, with doubled-down approaches meant to handle unsatisfactory testing results, like environmental sampling routines conducted to narrow down origin points of contamination.

A healthy shift

Suggested changes to normal production procedures, as well as other scenarios that can increase the chance of Listeria contamination, are listed in a U.S. Food and Drug Administration (FDA) document entitled “Control of Listeria monocytogenes in Ready-to-Eat Foods: Guidance for the Industry.” An environmental monitoring plan is recommended to mitigate the effect certain scenarios can have on the spread of Listeria in the plant. The guidance is very specific in its recommendations. They include:

    • Testing for Listeria to correct situations that could potentially lead to L. mono contamination, that focuses on both food contact and non-contact surfaces.
    • Sampling several hours into production, preferably just before cleanup.

The position implied from this guidance reflects a major healthy shift in the food safety industry. In the past, the discovery of Listeria in a facility was cause for panic and carried significant repercussions from regulatory bodies. Recent guidance from both Health Canada and the FDA and suggests that the agency wants facilities to find Listeria and effectively deal with it. No longer should a Listeria positive results be considered a failure — it can now be considered evidence that an environmental monitoring plan is working.

For more on environmental Listeria control, check out Neogen’s “The Process Control for Listeria Handbook.”


Category: Food Safety, Food & Beverage, Pathogens, Environmental Monitoring