Xylose Lysine Desoxycholate Agar is a differential selective medium for the isolation and differentiation of Gram Negative enteric pathogens, especially Salmonella and Shigella, from foods, pharmaceutical and clinical samples. The medium is particularly well suited for the investigation, since other microorganisms are strongly inhibited from growth.

XLD allows for the differentiation of pathogens of non-pathogenic lactose-fermenting species as well as non-pathogenic microorganisms that ferment neither lactose nor sucrose. It is particularly suitable for the isolation of Shigella species, which often show no growth due to other toxic growth factors.