Category Archives: Research

Listeria monocytogenes is an important foodborne pathogen, which is associated with high hospitalization and case-fatality rates. Outbreaks due to food contaminated with this pathogen continue to occur globally. In terms of risk management, major food trade associations have come together in a non-competitive manner to develop excellent guidance documents on the control of this pathogen. In addition, regulatory agencies responsible for food safety have made significant advances to help control L. monocytogenes.

Many countries around the world have established microbiological criteria for L. monocytogenes of 100 cfu/g for low-risk foods that do not support the growth of the organism. In contrast, the US currently has a “zero-tolerance” approach for all ready-to-eat (RTE) foods, regardless of their risk profile, therefore all positive test results lead to a recall. A blanket “zero-tolerance” policy for all RTE foods provides a very strong disincentive for zone 1 (product contact surface) testing, as well as a significant disincentive for finished product testing. More specifically, the challenge with a “zero-tolerance” approach for all foods is that all positive test results will lead to a recall, therefore potentially limiting the willingness to frequently sample. To compensate for moving away from a zero-tolerance approach for low-risk foods, industry would likely be willing to do a higher frequency of testing, which would enable them to generate and use more data, including next generation tools, to inform risk-based decision-making, long before committing products to commerce. Moreover, analysis of various alternate sampling approaches demonstrates that using a 3-class sampling plan can even be more stringent than the current 2-class presence-absence zero-tolerance approach. In addition to more stringent testing, the benefits of not doing a recall on low-risk foods that do not support the growth of L. monocytogenes and that contain only low levels of the pathogen include i) not wasting limited industry and regulator resources; ii) not losing consumer confidence, iii) maintaining a secure and sufficient food supply, iv) decreased food waste, v) avoiding negative effects on the environment, and vi) avoiding unnecessary costly food recalls.

In this review, we provide for an alternative approach to “zero-tolerance” and argue that some of the actions that could be undertaken as part of a country’s policy and/or regulatory approach to enhance the control of L. monocytogenes include: i) using alternate sampling approaches to the current 2-class sampling plans for low-risk foods that do not support the growth of the organism; ii) using big data to better inform microbial risk assessments; iii) performing a risk-benefit assessment; and iv) developing novel consumer food handling/risk communication strategies.

As evidenced by many years of studying this foodborne pathogen, a multi-pronged approach to the control of L. monocytogenes in high-risk RTE foods is necessary to reduce risk. This approach should include evidence-based, globally harmonized definitions for RTE and non-RTE foods, along with guidance on how these definitions should be applied in any policy on L. monocytogenes.