Oxford Listeria Selective Agar

According to ISO 11290, together with PALCAM it is one of the two selective media to be used, in parallel with ALOA, for the differentiation and isolation of Listeria monocytogenes in clinical samples, milk, cheese and in samples of different origin, even heavily contaminated. Using Columbia Agar as the base, lithium chloride is included to inhibit enterococci and Acriflavine to inhibit some other gram-positive and gram-negative organisms that may be present in such specimens. It is made further selective by the addition of multiple antimicrobials with Amphotericin included to inhibit any yeasts present. Aesculin is present as an indicator since Listeria monocytogenes will hydrolyse it and the associated reaction with the Ferric Ammonium Citrate gives rise to a black precipitate around the colonies. In most cases the appearance of Listeria colonies occurs after 24 hours of incubation. Available as powder to be reconstituted and supplemented or in ready-to-use 90 mm Petri plates.