XLD AGAR

XLD Agar is a selective differential medium for the isolation and quantification of Salmonella typhi and other Salmonella species from clinical and non-clinical samples. It is used for the identification of Enterobacteriaceae and for the microbiological testing of food, water and dairy products. The formulation suppresses competing flora and facilitates isolation of Salmonella and Shigella.
Yeast extract supplies vitamins and minerals, and sodium deoxycholate functions as a selective agent against many Gram-positive bacteria. Xylose, lactose and sucrose serve as fermentable carbohydrates, with phenol red indicating changes caused by carbohydrate fermentation. L-lysine allows differentiation of Salmonella by lysine decarboxylation. Sodium chloride maintains osmotic balance.
The medium also detects hydrogen sulphide production with the aid of sodium thiosulphate and ferric ammonium citrate to give characteristic black-centred colonies. These reactions are combined to distinguish Salmonella from other enteric organisms. Agar is the matrix that provides the solidity required for plate-based culture. XLD Agar is used for microbial limit testing as per USP and EP methods.

Designed for selective isolation and enumeration of Salmonella species, with differential reactions that help distinguish enteric pathogens through sugar fermentation, lysine decarboxylation and H₂S production.