Breakthrough test for food poisoning bug

By Rory Harrington

- Last updated on GMT

Related tags Bacteria Immune system

A new test to detect a bacteria that is a leading cause of food-poisoning is cheaper, faster and significantly more sensitive than existing assays, said the US body behind the breakthrough.

The USDA's Agricultural Research Service (ARS) announced the development of an advanced test to identify staphylococcal enterotoxin A, or SEA, a major cause of food-borne illness across the globe.

The assay will give food manufacturers another way of ensuring the safety of their products and help public officials trace the source of food poisoning outbreaks, said lead researcher Reuven Rasooly.

One billion

The new test can detect the toxin at levels one billion times lower than the current gold standard assay for SEA. Experiments on chicken, beef and milk demonstrated the assay reliably distinguishes active from inactive toxin and yields reproducible results, an ARS spokeswoman told

The test works by “taking advantage”​ of the fact SEA toxin has a double life, explained the ARS. Besides causing a range of gastroenteritis symptoms, SEA also acts as a superantigen - a molecule that activates large numbers of immune-system cells.

“The assay neatly exploits this trait by measuring proliferation of splenocytes, which are immune system cells produced in the spleen​,” said the ARS statement. “For the assay, the cells are kept alive in laboratory petri dishes.”

Practical and affordable

The ARS said the turnaround time of 48 hours for the SEA test is “comparatively fast”.​ Currently, regulatory agencies generally need to culture a bacterial contaminant before issuing a recall – which can take 3-5 days, said the spokeswoman. The new process is practical, said the body. Experienced technicians can quickly learn how to perform the test using standard laboratory equipment.

It is also cheaper than current tests. Using immunomagnetic beads that capture and concentrate the toxin, the cost of the assay is $ 3.88 per assay, which makes it affordable, said Dr Rasooly.

“The new assay is quantitative, reproducible and does not require lab animals,”​ added the ARS spokeswoman.

Rasooly and technician Paula M. Do developed the test at the ARS Western Regional Research Center in Albany, California. The ARS is the principal intramural scientific research agency of the USDA.

Related topics R&D

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