Salmonella TAG 24 and MAGDA™ Salmonella: Two Alternative Methods for Rapid Salmonella Testing
07 December 2006
Salmonella is one of the most common pathogens responsible for food poisoning. As even a small dose of salmonella is infective, its total absence in food products is a requirement in many countries. The food industry is thus required to implement a large-scale testing program for salmonella.
As the consumption of fast food increases, consumers are demanding ever-greater reassurance as to the safety of food products. In addition, the consumption of fresh salads, vegetables and other uncooked food is constantly increasing, applying pressure to reduce the delivery time from the producer to the consumer. The availability of rapid results for pathogens such as salmonella is thus becoming a real requirement.
The food industry is also increasingly releasing negative test results, and without a quick test that gives reliable results when they are needed, this practice is not possible. Raisio Diagnostics now provides two alternative ways to achieve the necessary speed and reliability.
TRANSIA® ADDITIVE GOLD 24
TAG 24 is a supplement to the established TRANSIA® salmonella gold, an enzyme immunoassay widely used for testing of the salmonella genus. It is a microtitration plate-based assay with antibodies targeted against unique lipopolysaccharides (LPS). It works with a simplified two-step enrichment procedure where no M-broth is needed to stimulate flagella growth. The test is used for raw and processed food as well as feed and environmental samples.
TAG 24, together with TRANSIA salmonella gold, forms a complete testing facility, and provides the first results only 24 hours after the start of enrichment. If a sample is positive, the confirmation by plating can be run directly from the same second broth as the TAG 24 to give a confirmed positive result.
TAG 24 salmonella gold uses ELISA technology with absorbance measurement as the detection method. The same detection technology is also used for salmonella gold, so the same instrumentation can be used both for the 24-hour method and the 36-hour method. This gives extreme flexibility as to how samples and results are handled. The tests can also be run under full automation with the TRANSIA ElisaMatic II or TRANSIA 4U automated ELISA processors.
MAGDA™ SALMONELLA
For users preferring plating as the detection method Raisio Diagnostics also offers a 24-hour method, MAGDA salmonella. This novel test offers high sensitivity with low capital investment in instrumentation. Culture-based plating as a detection method makes for easy and familiar handling, just like ISO.
The MAGDA salmonella 24-hour method combines traditional plating with a unique immunomagnetic capture, to shorten the enrichment time and have the results available in 24 hours as colonies on an agar plate. Proprietary enrichment supplement combined with shaking during incubation makes it possible to cut the enrichment time to only 5½ hours.
In order to have a representative sample, as much as 10ml of culture is used, providing excellent sensitivity in less time. PickPen® technology enables effective immunomagnetic capture of bead-bacteria complexes by collecting the magnetic beads and removing them from the liquid. Plating on agar plates of the user's own choice is performed with the same PickPen device.
It has a flexible silicon rubber tip that prevents the inconvenience of breaking the agar when plating, and makes plating easy without any additional steps. Confirmation of positive colonies can be made 16 hours after plating, giving a total assay time, beginning from the start of the enrichment, of only 24 hours.
