Rapid technology identifies food and pharma pathogens

Fraunhofer IGB has developed a stick test that can be used in situ to test for pathogens in many applications

Production of ImmuStick: Application of immune receptors onto the test strip. Photo Copyright: Fraunhofer IGB

At present, bacteria, fungi or viruses generally can only be detected with certainty by way of elaborate laboratory tests or animal experiments but the food and pharmaceutical industries would like to have faster tests to check their products. Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, in Stuttgart, are developing a test stick, similar to a pregnancy test stick, that quickly delivers a result.

The test, which will rapidly and cost-effectively identify bacteria, fungi or viruses, can be carried out directly in situ without laboratory equipment and specialist knowledge. The ImmuStick can even detect pathogens outside the body – on medical devices or in hospital wards for example.

The technology could also be of interest for testing human blood for germs or allergies, says Fraunhofer IGB’s Project Manager, Dr Anke Burger-Kentischer. The ImmuStick is a test strip onto which a few drops of fluid are applied. If the fluid contains pyrogens – fragments of pathogens – this is shown by a coloured strip in a viewing window.

It works via human immune receptors that are sensitive to certain pyrogens and which are applied to the surface of the stick. These are specially synthesised immune receptors and during their production a type of ‘place holder’, which is marked with a dye, is formed at the docking point of the immune receptors to which the pyrogens normally bind. When drops of a fluid containing pyrogens are then applied to the test strip, the pyrogens rush to the docking point on the immune receptor. The place holders marked with the dye migrate with the fluid and pyrogens through the test strip until they are visible in the viewing window. The colour signal thus indicates that the pyrogens are present.

The ImmuStick project was financed with money from the Fraunhofer Group ‘Discover Programme’. Through this scheme, the Group supports projects for the duration of one year to demonstrate the feasibility of a technology. Fraunhofer says that ImmuStick has passed this test. ‘We were able to show that it works very well for the bacterial pyrogen lipopolysaccharide (LPS). Together with industrial partners, we now want to develop it into a product’, says Burger-Kentischer. ‘We are currently testing further immune receptors that are specific for other pyrogens.’

Pyrogens are a problem for food and pharmaceutical facilities, for example, and on intensive care wards in hospitals where there are people with weakened immune systems who, when exposed to pyrogens, can become severely ill. For all such facilities, tests are frequently carried out and the surfaces of machines or medical devices are tested for pyrogens using swabs. However, to date these tests have been costly and laborious.

A widely used standard test is the detection of LPS, a structure that is present in the membrane of certain bacteria. At present this test takes around two hours. Furthermore, some pyrogens can only be detected in animal experiments. Thus envisaged applications for the ImmuStick are in the food and pharmaceuticals sector or in medical technology, but in principle, the ImmuStick would also be of interest for blood analysis.

Pyrogens in the blood often lead to blood poisoning, sepsis, from which many people still die today, especially weakened intensive care patients. ‘However, blood is a special challenge as it is complex and contains many constituent parts,' says Burger-Kentischer, 'but in the medium term we are aiming at blood analysis.’

As pyrogens also include certain allergy trigger factors, an application here would also be conceivable. In the food and pharmaceutical industries, for example, it is important that products are free of allergens. With the ImmuStick these could be detected quickly, cost-effectively and simply. Costly and laborious laboratory tests would no longer be needed or could be supplemented.

IGB researchers are seeking cooperation partners who want to further develop the ImmuStick to make it ready for the market.

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