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Going to battle against Listeria with new tools

Annette Fagerlund, postdoctoral fellow with Nofima, is rejoicing over new opportunities to stamp out the listeria problem. Tools are now available that make it possible to type every single bacterium.

This article was last updated more than two years ago.

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Annette Fagerlund

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Whole genome sequencing, which is the scientific term, determines the complete DNA sequence of the bacterium.

The bacterium Listeria monocytogenes probably represents the greatest threat to the Norwegian food industry. Year in and year out, significant resources are used to control and fight the bacterium, which, in severe cases, can be deadly for human beings.

Nofima is now calling for a national partnership between the food research institute Nofima and other research teams in order to build a national competence platform around whole genome sequencing of the dreaded bacterium.

Must keep up

It is impossible to produce food with a predictable good quality and which is safe to eat without a good standard of cleanliness. Satisfactory cleanliness is essential to prevent food scandals linked to food poisoning.

The overriding goal of the three-year project that Annette Fagerlund’s research is part of, is to gqin knowledge that can help Norwegian food producers achieve more sustainable, cost-effective and targeted cleaning, thus avoiding listeria contamination.

Fagerlund is of the opinion that this is important, especially for Norwegian food producers:

– There are not many people in Norway who are doing research on listeria. The Norwegian Institute of Public Health has started, as has the Norwegian Veterinary Institute. Nofima must keep up with the technology, on behalf of the food industry. When the public authorities have access to this technology and its applications, it is very important that someone on behalf of the food industry and at the same level, knows what it is all about, says the Postdoc.

Bacterial identification

What the scientist does, among other things, is to find out how the bacteria survive and are affected by the detergents and disinfectants that are commonly used in the food industry, and whether there is anything that can be done to make it easier to get rid of them.

Whole genome sequencing (WGS) is a powerful technology with a great potential, and it is developing at a rapid pace. One point is to identify, as far as possible, the type of bacteria one is dealing with. Through this, one can find out where the bacteria come from and how the bacteria behave. This type of bacterial identification is a more detailed classification compared to what has been achieved up to now. This is what sequencing is all about.

– We want to know “everything” about the bacterium. Only a few years ago, taking samples and getting a bacterium sequenced was a massive and complex operation. Now, technology is available which allows us, using a small computer chip, to get the answers we are seeking in real-time. In the future, we will probably be able to carry the sequencing equipment in our pocket when we visit food producers, instead of having to take samples of the bacterial flora back to the laboratory for further tests, says Annette Fagerlund.

In Norway, we are just beginning to sequence genomes, i.e. an organism’s complete genetic material, as part of the management of infectious desease. In recent years, the sequencing technology has evolved and is now much faster and more cost-effective, and large amounts of data will be collected that will give a lot of relevant information about bacteria, which is of great importance both for public health and for the Norwegian food industry.

The bigger picture

The Nofima scientist believes that there are several reasons for this work being prioritised and intensified in Norway.

– We still don’t have the bigger picture. We are unable to accurately determine where a bacterium originated. With regards to listeriosis cases in Norway, 30 per cent of infections are caused by the same listeria type, when typing is performed using conventional typing methodology. When there are so many seemingly similar bacteria strains, it is difficult to know where we should start to combat the problem. But even when we use genome sequencing there is a danger of reaching erroneous conclusions. Or that the wrong “culprit” is pointed out in the case of an infectious disease outbreak, Annette Fagerlund explains.

A study that the Nofima scientist has recently published in the internationally renowned scientific journal PlosONE, shows that virtually identical listeria bacteria are found in different production facilities.

– Direct contamination between factory premises is possible through, for example, suppliers of raw material or as a result of contact between factories. We need, therefore, an overview, at the genomic level, of the diversity of pathogens that is found in the different environments. To best interpret the results, we also need to understand how quickly small changes in the bacterial development take place in these environments, says the scientist.

Collaboration – important and justified

Annette Fagerlund is of the opinion that collaboration between a number of professional environments is important and justified. Nofima’s post-doctoral fellow points to the fact that genome data has a great potential as a tool to be used to better understand and to combat pathogenic bacteria practically.

  • Why do some survive in different environments whilst others succumb?
  • Why do only some cause diseases in humans?
  • Which of the listeria bacteria cause disease and which are harmless?

– Epidemiology is used in the resolution of infectious disease outbreaks and to find the sources of infection and transmission routes, and to understand relationships. We can identify which strains of bacteria cause diseases, detect new pathogens and identify patterns of antibiotic resistance. All through genomic data, says Fagerlund.

She compares the development of the technology to a train that moves faster and faster. A number of international research communities have already come a long way.

– Nofima just managed to board the train before it left without us. Now, we need to stay on board, Annette Fagerlund adds.

She believes that a national initiative will help Norway play an active role in the routine application of WGS analysis, and will generate new knowledge and be an effective use of resources, in contributing to increased food safety.

Much better by far

Even though we are talking about something as unpleasant as potentially deadly bacteria, the dedicated scientist can’t hide the fact that she is delighted with the new knowledge and the new technology that will bring an end to the listeria scourge.

– This new technology is going to plough on, for it is, so far, much better than what we have had up to the present time. And it is going to be so much fun! If we now bring about cooperation at a national level, we can suddenly take a massive step forward, says Annette Fagerlund.

With respect to research in general, and in particular in the use of sequencing technology, in the battle against listeria, it may, however in this context be appropriate to quote the legendary words of Sir Winston Churchill:

“Now this is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.”


Food Micro Control

Control of microorganisms is a major challenge for food producers. Nofima’s strategic programme, Food Micro Control, provides new knowledge and skills for understanding the growth, survival, activity and function of microorganisms in food and food production environments, and is one of ten strategic research programmes in the Food Division. The programmes underpin our long-term knowledge building and are vital if Nofima is to be a leading international business-oriented food research institute

Through this programme, we develop and sustain our microbiological competence in the fields of food safety, ford quality, health and analysis methodology. The programme, in close cooperation with other participants in the food chain, gives Nofima the basic know-how needed to solve the challenges that the food industry faces

The programme has research activities in three principle areas:

1) Bacteria in food

2) Bacteria in the production environment

3) Method platform for molecular analyses of microorganisms

Annette Fagerlund works on biofilm and sequenced listeria strains in a three-year project funded by Research Funding for Agriculture and the Food Industry (FJM formerly FFL), the Technical Committee for Industrial Detergents and Disinfectants and Bama Gruppen AS. In this work, bacteria strains from two terminated projects financed by FJM and the Fisheries and Aquaculture Research Fund are used.

Listeria monocytogenes:

  • L. monocytogenes is an environmental bacterium that is found “all over the place” – in soil, water, fish, meat, fruit and vegetables.
  • The bacterium can cause listeriosis; an extremely serious disease with a 20-30 per cent mortality rate. The risk groups are, in particular, people with impaired immune systems, elderly over the age of 65 and pregnant women.
  • Almost 100 per cent of human cases of the disease are caused by food that is contaminated with L. monocytogenes.
  • Risk products include long shelf-life, cold stored products where listeria can grow.
  • A large amount of resources is used to control and to combat the bacterium.
  • L. monocytogenes have significant health-related, social and financial consequences.

Source: Norwegian Institute of Public Health, the Norwegian Veterinary institute and Nofima

Whole genomes sequencing (WGS)

  • By way of sequencing, one gets access to the genetic code in a genome. The composition of the genome determines the microbes’ identities and characteristics.
  • Whole genomes sequencing provides fast and cost-effective generation of large quantities of sequence data.
  • Large quantities of data results in the need for analysis methods and analysis competence.

 Food safety and quality  

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