Listeria Agar Base Palcam Iso 11290-2 1141 Condalab

Listeria Agar Base Palcam when used with supplements, is a selective and differential medium for Listeria spp. It is recommended by ISO 11290 for the detection and enumeration of Listeria monocytogenes in food products and clinical sample. It has also been used for environmental samples and after a primary and se ry enrichment stage, using Listeria Enrichment Broth Base (Cat.CL-1120). It can assist with the differential diagnosis of Listeria monocytogenes using a double-system indicator: Esculin/Iron and Mannitol/Phenol red.

All Listeria species hydrolyse the esculin to esculetin, which reacts with iron ions producing a blackening of the medium. Lithium chloride that is included in the medium, along with ceftazidime, polymyxin B sulphate and Acryflavine from the supplement, inhibit the growth of the non-Listeria accompanying bacteria present in foods, which can hydrolyse the esculin. Peptones and maize starch provide a rich nutrient base for growth. Yeast extract is the source of vitamins, particularly of the B-group. Glucose is the fermentable carbohydrate. Ferric ammonium citrate improves the growth of L. monocytogenes.

The Mannitol/Phenol red differentiation system is used to differentiate Listeria spp that do not ferment mannitol from other species that occasionally grow in the medium such as enterococci or staphylococci. Differentiation is achieved by the acid increase in the media, causing the phenol red indicator to change the colour of the medium from red to yellow. Confirmation of Listeria is done by biochemical and serological identifications tests.