Isolate, enumerate and differentiate Listeria species and Listeria monocytogenes from food samples with Thermo Scientific™ Oxoid™ Chromogenic Listeria Agar (ISO) (Dehydrated). Chromogenic Listeria Agar (ISO) contains lithium chloride, polymyxin B, nalidixic acid, and amphotericin which act to inhibit non-target organisms. A combination of chromogenic and phospholipase enzyme reactions easily differentiate Listeria monocytogenes (blue colonies surrounded by an opaque halo) from other Listeria spp. (blue colonies without an opaque halo).
Listeria monocytogenes is the most common pathogenic
Listeria spp. and has been shown to be pathogenic to both humans and animals. Chromogenic Listeria Agar (ISO) is designed to identify
Listeria spp. based on their utilization of a chomogenic substrate.
- Easy-to-read: chromogenic and phospholipase enzyme reactions easily differentiate Listeria monocytogenes from other Listeria spp.
- Adheres to ISO 11290-1:1997 standards.
- Superior to PALCAM and Oxford medium for the isolation of Listeria monocytogenes1.
The presence of the chromogenic substrate for the detection of ß-glucosidase (an enzyme common to all
Listeria spp. and to a few strains of
Enterococci and
Bacilli) results in chromogenic activity.
Further differentiation of
Listeria monocytogenes and other
Listeria spp. is facilitated by the addition of phosphatidylinositol or lethicin substrate for the detection of phospholipase enzyme.
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1. Gently agitate the bag; then using a microbiological loop, inoculate onto Chromogenic Listeria Agar (according to Ottaviani and Agosti) and a second selective medium (e.g. PALCAM Agar - CM0877 & SR0150). Incubate at 37°C for 24h ± 3h, and if necessary, for an additional 24h ± 3h (PALCAM Agar should be incubated under micro-aerobic conditions for best results).