Listeria monocytogenes test

Listeria monocytogenes are bacteria that belong to the Listeria family. There are several species within this family, but Listeria monocytogenes is the only species that is pathogenic to humans. It is important that you preventing consumers against a Listeria bacteria.

From the Dutch Food and Consumer Product Safety Authority (NVWA), it is mandatory for food business operators to manage the risk of Listeria monocytogenes. This includes the testing of each produced food item, which must be based on n=5 procedure. None of these 5 samples should give an abnormal result.

Applicable requirements for Listeria monocytogenes are:

- Presence/absence studies: absent in 25 gram sample, or

- Counts: <100 cfu per gram of sample

Why testing for Listeria bacteria is so important?

Infection with Listeria monocytogenes bacteria can lead to the disease Listeriosis. Although in most cases an infection will only cause flu-like symptoms.

In certain cases, Listeria can cause serious consequences especially for pregnant women, elderly people, young children and people with reduced immunity.

Listeria bacteria are therefore considered as dangerous when multiplied by circumstances. People who have contracted a serious listeria infection can become seriously ill and this can even be fatal. It is important to test the presence of Listeria bacteria ensuring safety of your products.

What can Listeria bacteria be present in?

Listeria monocytogenes bacteria are found primarily in ready-to-eat products, such as:

- Processed meats

- Raw meat and fish

- Pre-packaged vegetables

- Cheeses

- Eggs

- Milkproducts

You may remember the large Listeria monocytogenes contamination at processed meat producer Offerman in 2019. Following this contamination Offerman unfortunately had to close their facility.

A Listeria monocytogenes test must be done by a certified laboratory. In this way, the Listeria analysis is always reliable.

How long does a Listeria analysis at TLR take?

The turnaround time of our analyses are always short. We always strive to give you the results of the analyses as soon as possible. You will have the first results of a Listeria rapid test within 72 hours.

If a suspicious colony is detected, confirmation takes an additional 24 hours.

The cost of a Listeria lab test

The cost of a Listeria analysis depends on whether it is a product or environmental sample analysis. Also, the cost depends on the amount of sample to be analyzed.

An analysis of 25 grams of sample is common, but larger quantities (125 grams or 325 grams) can also be analyzed. It is also possible to use several samples simultaneously as a mixed sample or to apply an n=5 procedure. Therefore, please feel free to contact us for our possibilities or request a quote directly.

How does the Listeria analysis work?

Our analysts will prepare samples for analysis upon sample receipt until the end of the afternoon. The samples will then be placed in incubators for the required 24 hours of bacterial accumulation.

The next day, these accumulations will be transferred to agar plates specific for Listeria monocytogenes bacteria. These plates are incubated for 48 and then assessed for specific growth. A confirmation of specific Listeria monocytogenes bacteria takes place by means of a second plate specific for Listeria.

Our method is RvA-accredited (L059) and equivalent to NEN-EN-ISO 11290-1.

THT testing and Challenge testing

There are two Listeria testing methods. At TLR it is also possible to perform THT tests (shelf life tests) or Challenge tests on your products with regard to Listeria monocytogenes.