Easy Cheesey Listeria Detection

They say you should “always open with a joke”. So, here goes. Why did the one-legged clown leave the cheese circus?

Because he couldn’t get his Stilt on! 😀

Anyway, moooooving on…

In the UK you can easily find pasteurised cheese in supermarkets. However, it is also possible to buy unpasteurised cheeses from farm or specialist cheese shops. To ensure it is safe for consumption, all cheese is tested for the presence of Listeria.

Dairy items can often be tricky to test for pathogens. Cheeses from unpasteurised milk can be particularly challenging as they often contain high levels of background microflora such as Enterococci. A high bioburden in a sample can mask the presence of Listeria and thereby cause detection problems in some systems.

Recently we received information that our Solus Listeria ELISA kits were perhaps not working optimally for the detection of Listeria in certain cheeses. Our Solus Pathogen Testing systems have AFNOR and AOAC accreditation. That means that, during independent testing, Solus kits pass all accreditation criteria. As a result, we weren’t too worried. However, as the concern had been raised, we decided to carry out in-house testing to ensure that our kits still produce the results we expect.

Life doesn’t get grater’ than cheese testing…

Solus purchased a pasteurised Stilton, a pasteurised Danish blue and an unpasteurised cheese for investigation. We then carried out testing using the ISO method in parallel to our own Solus Pathogen Testing System.

To see the full report click here.

*Spoiler alert* We were able to detect Listeria monocytogenes and Listeria species using the Solus Pathogen Testing system in accordance with the ISO results.

Brie aware…

Our Pathogen Testing System consists of Solus ELISA kits and DS2 automation with associated consumables and dedicated media. The Solus system is as reliable and robust as possible, but no system is perfect. Solus provide clear, specific instructions with our kits but due to the biological nature of the assay there is room for error. To get the best results from Solus products, please follow all of our instructions and prepare all media in accordance with the manufacturer’s instructions.

So, in conclusion, how do you test for Listeria in cheese? Caerphilly! 😉



At Solus, we don’t like to sit back on our laurels and assume we’re doing a great job. We are constantly working to test and develop our kits to ensure that our customers get the best possible product. We welcome feedback as it gives us the opportunity to improve. Feel free to let us know how we’re doing by completing this short survey.


Image: Cheese Platter CC BY-SA 3.0 Nick Youngson / Alpha Stock Images