Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria. This is one such medium and is a selective medium for the isolation and presumptive identification of Listeria monocytogenes from clinical and food samples. The medium is made selective by the inclusion of Lithium chloride, Ceftazidime, Polymixin B, Nalidixic acid (to suppress other bacteria) and Amphotericin B (to suppress yeasts and fungi). With the combination of both the chromogenic substrate and phospholipase C enzyme reactions, it is possible to differentiate L.monocytogenes from other Listeria spp. Users should be aware that some strains of L.ivanovii are capable of producing an opaque halo, highlighting the need to confirm presumptively identified colonies.
Colorex™ Listeria (ISO)
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Storage Conditions | 2-8°C – Store in the dark |
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Product Description
Organisms | Ref. No | Result |
Listeria innocua | NCTC 11288 | Blue colonies with no halo |
Listeria monocytogenes | NCTC 11994 | Blue colonies with opaque white halo |
Escherichia coli | NCTC 12241 | Inhibited |
Enterococcus faecalis | NCTC 12697 | Inhibited |
Saccharomyces cerevisiae | NCPF 3178 | Inhibited |