5 February 2007

Fraser Broth^PLUS and Half Fraser Broth^PLUS are recently-introduced variants of Lab M’s standard Fraser Broth medium for the isolation of Listeria species. The new media are formatted to give improved results in both traditional culture and ELISA methods. In common with all of Lab M’s Fraser Broth range, they meet the specifications of the ISO 11290 standard for the detection and enumeration of Listeria monocytogenes. Fraser Broth is traditionally used as a secondary enrichment medium for the isolation of all Listeria species. With the incorporation of half strength supplement, it can also be used as a primary resuscitation or enrichment medium.

Fraser Broth^PLUS and Half Fraser Broth^PLUS differ from conventional formulations in the inclusion of selective agents in the base medium. The ferric ammonium citrate (FAC) component is provided as a supplement to be added after sterilisation. This format has been shown to give improved selectivity with pure cultures and food samples. The option to omit FAC from the final medium is advantageous where ELISA techniques are used, reducing the incidence of false positive results.

Both the new media are tested in accordance with, and meet the technical specifications of the ISO/TS 11133-2 standard for the microbiology of food and animal feedstuffs.