Listeria Swab is designed to minimise the risk of contamination of work areas or finished products by Listeria spp. in particular L.monocytogenes. Each self-contained peel pouch consists one green-capped plastic shaft with calcium alginate tip and one labeled and sealed tube containing selective culture medium with indicator. Listeria Swab is sterilised by irradiation.

• Peel back the packet wrapper to reveal both the cap of the swab and the cap of the culture tube
• Remove the swab and sample designated area
• Remove the cap of the culture tube and discard
• Insert the swab in the culture tube and push down firmly to immerse the swab completely
• Note on the tube details of the sample taken

The test is based upon an enhanced Esculin medium formation. The hydrolysis of Esculin by Listeria spp. results in the formation of a distinctive black-coloured precipitate. The tip of the swab used in the test is composed of calcium alginate. The formulation allows the tip to dissolve completely when immersed in the medium, ensuring that all organisms collected during sampling will come into direct contact with the medium.

If the colour of the media has changed from light brown to black/dark brown, this indicates the presence of Listeria ssp. in the sample. The colour change starts in the area directly around the swab and will spread outwards until all the media has changed. Colour change after 24 hours should be recorded as a positive result. If there is no colour change after 24 hours, incubate for a further 24 hours at 37 °C. If the colour has changed after 48 hours, record the result as positive.