Listeria, Listeria monocytogenes  Control and Legislation

Contents:

The importance of Listeria and Listeria monocytogenes (Lm) 
Lm overview
Microbiological Criteria for Foodstuffs legislation 2073/2005 
Potential future legislation: Industry Listeria Group Tech Summary – EU micro criteria proposals 1 5 24
Unintended negative food safety consequences of changing 2073/2005
Industry Listeria Group (ILG)
Further reading
CFA presentations
Articles on our website

The Importance of Listeria and Listeria monocytogenes

Safety is the cornerstone of the UK chilled prepared food industry. CFA in 1989 published the first detailed best practice guidelines for chilled food production setting out key principles, including the design and management of factory, equipment and production areas, raw material and process requirements, staff hygiene rules and chilled chain performance requirements.

Of the various microbiological issues addressed through that, and CFA’s subsequent portfolio of best practice guidance, Listeria species, and specifically Listeria monocytogenes (Lm) is the key focus organism for ready to eat (RTE) foods.

Lm Overview

Lm is a pathogenic Gram positive environmental bacterium with a high human mortality rate. Lm is one of 28 Listeria species, many of which are genetically distant from it.

Lm is notably resistant to heat, to the effects of cold storage and to water activity, surviving freezing and dry conditions, as summarised in the table below:

 Factor Growth Limits Survival
Lower Optimum Upper
 °C -2.0 to 3.0 30-37 45 -18
 pH 4.0-4.3 7 9.6 3.3-4.2
 aW 0.92 (0.90 glycerol) 0.99 <0.90
 NaCl (%) 12 >20
 Atmosphere Facultative anaerobic & microaerophilic  – able to grow + O2 (e.g. vac pack or MAP)

 

Since Lm, as with other Listeria species, is an environmental contaminant occurring widely in both agricultural (soil, vegetation, silage, faecal material, sewage, water), aquacultural, and food processing environments some foods are more likely to be contaminated e.g. raw vegetables, fish and meat.

Lm grows particularly well in proteinaceous foods.

Although frequently present in raw foods of both plant and animal origin, sporadic cases or outbreaks of listeriosis are generally associated with ready-to-eat (RTE), refrigerated foods, and often involve the post-processing recontamination of cooked foods. A 2022 WHO/FAO report found that of 88 outbreaks where a root cause was identified, 77 were caused by post-process contamination. Environmental hygiene control is critical to RTE food safety.

Control of Lm for many RTE products typically requires a stringent application of Good Hygienic Practice and other supportive programs. These prerequisite programs, together with HACCP provide a successful framework for the control of Lm.

Key elements of control are:

  • proactive systematic collection and use of food production environmental swabbing data to identify issues and demonstrate control, including with suppliers of RTE ingredients/components.
  • setting shelf life requiring knowledge of foods’ physicochemical properties combined with durability studies and a stream of food and environmental data and Supplier Quality Assurance, particularly of RTE components

EU Microbiological Criteria for Foodstuffs Regulation 2073/2005

This Regulation has helped facilitate delivery of the effective control of Listeria monocytogenes in foods. It has done this by allowing industry to focus efforts on controls to prevent contamination of foods through effective raw material, people and environmental controls whilst using testing of product to verify the efficacy of these controls to ensure the safety of product throughout its shelf life. Much data has been collected on products throughout shelf life, and on environmental management to verify ongoing safety – more than 4 million datapoints by the UK chilled prepared food industry alone, through CFA.

This holistic approach to management of the risk from L. monocytogenes has contributed to the low rate of listeriosis, for example in the UK which is consistently markedly below the overall European listeriosis rate.

CFA Members adhere to the application of HACCP-based principles, Good Hygiene Practices and action plans agreed with retail and other customers, national or European-level guidelines or [1]Guides. These practices include continuous compliance verification conducted by the FBOs themselves, their customers (particularly in the case of own label foods), third party auditors and respective Competent Authorities.

Potential Future Legislation

The EC in 2023 engaged with Member States to seek a common understanding of the rules although this is some 17 years after they came into effect. A recent European Court case raised clarifying points regarding the interpretation of criteria, which confirmed the UK chilled prepared food industry’s and the UK Government’s interpretation. However, it has resulted in proposed major changes to Lm criterion 1.2b in Regulation 2073/2005 (from positive release to not detected throughout life) and, potentially, to established enforcement approaches to shelf life validation and verification of ongoing control.

Proposed comments on change to criterion 1.2b

1. Lm is ubiquitous in nature and puts a constant pressure on contamination of raw material and production environment. The main effort to avoid Lm contamination of products put on the market should be on GMP/GHP and a “search and kill” strategy to eliminate Lm from the production environment before the product is put on the market. All efforts put on end product control, including challenge testing, diverts financial resources away from cleaning and disinfection and environmental hygiene monitoring, which are critical prerequisites requirements of HACCP. It should also be kept in mind that the food safety criteria of 2073/2005 have to be met by all operators, including SMEs which often have limited means for such testing, which at the end may lead to less testing at critical stages of production or diverting funds away from critical hygiene control to testing.

2. We recognise the importance of the Microbiological Criteria for Foodstuffs Regulation 2073/2005 and how it has helped facilitate delivery of the effective control of Lm in foods. It has done this by allowing industry to focus efforts on controls to prevent contamination of foods through effective raw material, people and environmental controls whilst using testing of product to verify the efficacy of these controls to ensure the safety of product throughout its shelf life. Many millions of datapoints have been collected by industry on products throughout shelf life, and on environmental management to verify ongoing safety. This holistic approach to management of the risk from Lm has contributed to the low rate of listeriosis, for example in Ireland and the UK which is consistently markedly below the overall European listeriosis rate. The legislation is effective as it stands, when enforced, including commercially.

3. Our Members adhere to the application of HACCP-based principles, Good Hygiene Practices and action plans agreed with retail and other customers, national or European level Guides. These practices include continuous compliance verification conducted by the FBOs themselves, their customers (particularly in the case of own label foods), third party auditors and respective CAs.

4. Shelf life establishment using storage trials coupled with day of production (production hygiene) and end of life (monitoring appropriateness of shelf life) sampling of food, with trend analysis including extensive data from environmental sampling has been used successfully by the Irish and UK chilled RTE food industry supplying its and Ireland’s EUR15+bn market for more than two decades. This approach takes into account the effect on Listeria monocytogenes of raw material, process and environmental controls as well as behaviour in the food. EFSA/ECDC epidemiological (Table 1 and Figure 1 of v18. 1 TLD) and industry data demonstrate this approach assures safety as it contributes to Ireland and the UK’s low national listeriosis incidence, which is consistently well below the European average.

5. Lm may be present at low levels in food products (and testing positive in a 25g sample), but without posing a problem at the end of shelf life. This is for example in the case in fresh products with a natural competitive microflora. Such low levels of Lm contamination are likely to be not correctly reflected in challenge testing because the level of inoculation in challenge testing is much higher than natural, and Lm often grows more rapidly than when naturally occurring. The proposals take no account of differing virulences of Lm strains.

6. Putting a zero tolerance of Lm in 25g (i.e. Not Detected) during the total length of the durability period on the market may result in products testing negative (absence) when leaving the immediate control of the producing FBO while later in the chain these products may test positive (presence) on 25g without a clear view on the history of the sampled products (e.g. local temperature abuse in the distribution chain, cross-contamination at the point of use or sale e.g. delicatessens/foodservice). Post-process contamination has been shown by FAO/WHO[1] to be the primary root cause of 79 out of 88 listeriosis outbreaks where a root cause was identified. Even without temperature abuse, Lm may grow at low temperatures from initially undetectable levels at or immediately after production, which adds to the uncertainty whether a positive in 25g during shelf life is of real concern. Temperature control is critical to minimising potential for growth of Lm. There is no EU legislation for commercial temperature performance. In addition, domestic fridges perform variably and consumer information and education in addition to improvements in performance are needed not only to protect food safety and public health, but also to reduce food waste from spoilage (see https://www.ecff.net/wp-content/uploads/2018/10/ECFF_letter_to_European_fridge_manufacturers_February_2013_ID_22201_CECED-1.pdf).

7. It is likely that extending the zero tolerance of Lm in 25g and pairing its application to delivering proof that the product will not exceed the limit of 100 cfu/g throughout the remaining shelf life, will result in many practical problems, in particular when products are produced in one MS and distributed in another. It may prove to be very time consuming to provide such proof “in time” to the questioning CA, leading to unnecessary recalls, food waste and reduced food security, and without a sound scientific basis.

8. In addition, compliance with such a proposal for 1.2b would require either reformulation to kill Lm (e.g. pH<3.3), which would render many foods unpalatable, or in-pack processing (e.g., thermal, HPP, irradiation), which would be of extremely limited applicability without destroying food organoleptic and structure or having low public acceptability of the technology (e.g., irradiation). Many foods would not be viable on the market despite their not presenting food safety risk. Much more emphasis is instead needed on environmental controls and active management and enforcement.

9. We propose instead of zero tolerance/Not Detected in 25g for criterion 1.2b that the current legislation is enforced at all stages of the supply and distribution chain as that approach is shown to be effective at reducing listeriosis, as shown in the ECDC/EFSA One Health data for Ireland and previously the UK. Failing this, a quantification limit of 20 cfu/g throughout life would reflect public health protection and sustainability policy needs.

Unintended negative food safety consequences of changing 2073/2005

Negative impacts of potential changes to 2073/2005 are the most important food safety policy matter for the UK chilled prepared food industry. The UK industry can demonstrate through hard data (epidemiology, food and environmental sampling) that its approach is more effective from a public health perspective than that in other major European countries and across Europe, the UK (and Ireland’s) listeriosis rate consistently being some half that of Europe as a whole.

Consequences of the following potential changes to the Regulation 2073/2005 are set out on these linked pages:

The full draft Industry Listeria Group Tech Lobbying Document (12/4/24) has been agreed by UK industry, major multiples and European federations and includes additional data not published on these linked pages.

See also: Listeria and Zero Tolerance

Industry Listeria Group

Aims

The ILG was established by CFA in May 2021 to:

1. share intelligence on and track UK, EU and other international developments (e.g. CODEX/WTO) in relation to Lm legislation and standards

2. to assess potential impacts on food safety and established best practice in the control and enforcement (including commercial) of potential and proposed changes to requirements, and

3. prepare for, communicate to industry, the trade and respond to Government and agencies on any proposed changes to requirements with a view to protecting food safety best practice

The ILG meets at least monthly, is chaired and managed by CFA’s Karin Goodburn.

ILG Members

In addition to CFA members and UK major multiples members of the Industry Listeria Group include:

Association of Independent Meat Suppliers British Frozen Food Federation
British Meat Processors Association British Retail Consortium
The British Sandwich & Food to Go Association Chilled Food Association
CLITRAVI (European meat products association) Dairy UK
European Chilled Food Federation European Smoked Salmon Association
European Sprouted Seeds Association Fresh Produce Consortium
Provision Trade Federation Salmon Scotland
Seafish Specialist Cheesemakers Association

 

Further Reading


CFA Presentations

Articles on our website

Reference

[1] For example, “European Guide to Good Practice for Smoked and/or Salted and/or Marinated Fish” published by the European Commission. The Guide was endorsed by EU Member States at the 3/7/18 meeting of the Standing Committee on Plants, Animals, Food and Feed (PAFF).

 

1 May 2024