April 11, 2006
Ahmed ElAmin
A new Listeria assay allows processors to simultaneous detect and differentiate between two species in a single test for food products.
Increasing regulatory emphasis on food safety in plants and the cost of recalls has spurred food companies to seek faster ways of detecting pathogens.
bioMÈrieux said its new Vidas Lduo test now enables the simultaneous detection and differentiation of Listeria spp and Listeria monocytogenes in a single test.

“By working in routine with the simultaneous detection of Listeria spp and Listeria monocytogenes, laboratories can improve their efficiency and better anticipate the risk of Listeria contamination,” the company stated in a press release. “The use of Listeria spp as an early alert indicator reinforces the control of this pathogen. The immediate result for Listeria monocytogenes optimizes the confirmation procedure.”
bioMÈrieux, which is based in France, said the new immunoassays allows testers to synthesise antibody fragments that reduce non-specific interactions with foods for increased specificity.
The use of these highly specific antibody fragments also improves sensitivity through a more rapid diffusion in the sample, the company claimed.
The company’s Vidas line is an automated system for food-borne pathogen detection. The system recently obtained official validation by AFNOR, France’s standardisation agency, in compliance with ISO16140.
Listeria monocytogenes causes listeriosis in humans. A wide range of contaminated foods is associated with its transmission, including meat, dairy, fish, shellfish and vegetable products. The laboratory methods used to detect L. monocytogenes in food have improved in recent years and the organism has been found, but usually in small numbers, in many foods.
Listeria is killed by pasteurisation and cooking. However, in certain ready-to-eat foods such as hot dogs and deli meats, contamination may occur after cooking but before packaging.
In humans, Listeria monocytogenes may cause severe pathologies, such as meningitis, septicaemia and encephalitis, as well as abortions. Groups at greatest risk include pregnant women, neonates, immunocompromised patients and the elderly.