A new ultrasensitive chemiluminescence-based method has been developed by scientists for the direct detection of salmonella and listeria monocytogenes.

Because of the simplicity and sensitivity, the scientists say the test is significantly faster than conventional methods and can be carried out in the field.

Current testing methods usually require the growth of bacterial cultures in a containment laboratory. A conclusive result based on standard diagnostic techniques generally takes two to six days.

Researchers working with Urs Spitz and Doron Shabat at the University of Tel Aviv, Nemis Technologies, Zurich University of Applied Sciences, and Biosynth have now introduced a new and efficient method for the ultrasensitive and significantly faster detection of Salmonella and Listeria.

The method is based on chemiluminescence – the emission of light resulting from a chemical process.

The simplicity of the tests allows for both enrichment of the bacteria and their detection in a test tube, with no further sample preparation, so no containment laboratory is required.

The chemiluminescence probes have proven to be about 600 times more sensitive than conventional fluorescence probes.

The success of this technique is due to two specially developed probe molecules made by combining a luminescent substance (a phenoxy-dioxetane) with a “trigger”.

The intensity of the glow can be used to quantify the concentration of bacteria. The tests are so sensitive that, for example, a count of ten salmonella can be detected within six hours of enrichment. Even dried bacteria can be swabbed from surfaces and detected.

The researchers are confident that their new method can be used more broadly to develop specific chemiluminescence probes for other bacteria.