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04.12.2019 - Microbiology

Environmental investigations for Listeria monocytogenes in food businesses

Diseases and recalls caused by Listeria monocytogenes have increased in recent years in Germany and the EU (BfR 2017, BfR 2018).

Since listeria are microorganisms that are widespread in our environment, persist in biofilms, and can multiply in food even under unfavorable environmental conditions, these bacteria can be regularly detected in relatively many food groups such as meat and meat products (BfR, 2017). If the statutory food safety criteria for Listeria monocytogenes from Regulation (EC) No 2073/2005 on microbiological criteria for food are exceeded, products on the market must be recalled. Numerous examples of this are publicly accessible in the European Rapid Alert System RASFF (European Union, 2018).

Food business operators whose products may be contaminated with Listeria monocytogenes are obliged by legal requirements under EU hygiene law (Article 4(3) of Regulation (EC) No 852/2004 on food in conjunction with the provisions of Regulation (EC) No 2073/2005 on microbiological criteria for food) and due to the duty of care to conduct appropriate self-controls.

These obligations not only concern carrying out food examinations but also conducting environmental investigations. For Article 5(2) of Regulation (EC) No 2073/2005 on microbiological criteria for foods states: "...food business operators producing ready-to-eat foods that may pose a risk to public health from Listeria monocytogenes must test samples from processing areas and equipment for Listeria monocytogenes as part of their sampling plan..."

Because there are no specific legal requirements concerning the scope of environmental monitoring for Listeria monocytogenes, guidelines or recommendations can be used as references. The " Guidance for Good Practice in Conducting Microbiological Self-monitoring in the Self-production of Ready-to-eat, Pre-cut Fruit and Vegetable Products in Retail" recommends an annual environmental examination for Listeria monocytogenes at one cleaned and disinfected spot per year (BLL, 2016). Other German hygiene guidelines currently do not provide information on the scope of environmental monitoring for Listeria monocytogenes. Accordingly, each affected company must decide over the handling and conduct of listeria monitoring as part of its duty of care.

The following aspects have been considered during the implementation of listeria environmental monitoring and the interpretation of results:

• Listeria monocytogenes are bacteria that are widespread in our environment and therefore regularly occur in many raw animal and plant foods (BfR, 2017; BfR 2018). These germs also regularly appear in food companies as they are introduced via raw materials and humans.
• The goal of a food company must be to prevent permanent colonization with Listeria monocytogenes in the company. These areas are particularly wet areas that are not regularly cleaned and disinfected or are not completely reached during cleaning and disinfection. These include areas such as gullies and evaporators or evaporator trays of cooling systems.
• Individual positive findings with Listeria monocytogenes are virtually unavoidable in most food companies that work with unpackaged raw animal and/or plant foods. The key is to prevent permanent colonization or biofilm formation with Listeria monocytogenes through hygiene measures.
• Environmental monitoring for Listeria monocytogenes should therefore aim to provide insights into the following aspects: how often Listeria monocytogenes is found in the environment, where it is found, and how successful the performed cleaning and disinfection measures are. Therefore, both investigations during ongoing operations and after cleaning and disinfection are beneficial for this status assessment. However, investigations during ongoing operations should predominate.
• Depending on the examination site, it may be useful to work with sponges or swabs during sampling. For larger surfaces, sponges are preferred to sample areas of 100cm², for example. For hard-to-reach places, such as cracks, it is necessary to work with swabs.
• Conducted laboratory examinations should be performed using suitable qualitative methods after enrichment to achieve high sensitivity and detect the smallest levels of germs.

In our laboratory, we conduct daily examinations for Listeria monocytogenes in foods but also within the scope of environmental monitoring. Therefore, we have high expertise and experience in these areas.

Simply inquire with our customer consultants!

Literature

Association for Food Law e.V. (BLL) / Federation of the German Food Trade e.V.: Guidance for Good Practice in Conducting Microbiological Self-monitoring in the Self-production of Ready-to-eat, Pre-cut Fruit and Vegetable Products in Retail (12/2016), last accessed: 02.10.2018 (BLL, 2016)

Federal Institute for Risk Assessment (BfR): Zoonosis reporting by the BfR. Pathogens of Zoonoses in Germany in 2015, last accessed: 01.10.2018 (BfR, 2017)N

Federal Institute for Risk Assessment (BfR): Press release by the BfR from 27.09.2018. Listeriosis: Rare, but Dangerous for the Elderly, Pregnant Women, and People with Weakened Immunity, last accessed: 01.10.2018 (BfR, 2018)

European Union: RASSF Annual Report 2017, last accessed: 02.10.2018 (European Union, 2018)

Regulation (EC) No 852/2004 of the Commission of 29 April 2004 on the hygiene of foodstuffs (OJ L 139, 30.04.2004, p. 1) in its current version

Regulation (EC) No 2073/2005 of the Commission of 15 November 2005 on microbiological criteria for foodstuffs (OJ L 338, 22.12.2005, p. 1) in its current version