KM0013 Xylose Lysine Deoxycholate (XLD) Agar is used for the isolation and detection of Salmonella and Shigella spp. in clinical specimens, food, and environmental samples.
Xylose Lysine Deoxycholate (XLD) Agar is used for the isolation of Salmonella from food and animal feedstuffs when used according to ISO 6579:2017, ISO 11133:2014. The formulation conforms to CLSI M22 and European, United States and Japanese Pharmacopeia requirements. KM0013 is recommended for clinical specimens as a standard, supplementary or primary isolation medium by the UK Standards for Microbiology Investigations.
Xylose Lysine Deoxycholate (XLD) Agar has a pH of 7.4, leaving it with a bright red appearance due to the indicator phenol red. Sugar fermentation lowers the pH and the phenol red indicator registers this by changing to yellow. Most gut bacteria, including Salmonella spp., can rapidly ferment the sugar xylose to produce acid; Shigella spp. cannot do this and therefore remain red. Once the xylose has been used, Salmonella spp. decarboxylate lysine leading to a reversion to an alkaline pH. Additionally, Salmonella spp. (but not Shigella species) are able to reduce thiosulphate to hydrogen sulphide which reacts with ferric ions to produce the black pigment iron sulphide. Salmonella spp. may, therefore, be differentiated since colonies have a black centre on this medium.
