Technical Data
XLD Agar (Powder)
Microbiological Grade
Storage RT    Shipping RT
Components shown as g/liter:
Yeast Extract3.0
Ferric Ammonium Citrate0.8
Sodium Deoxycholate2.5
Sodium Chloride5.0
Phenol Red0.08
Sodium Thiosulfate6.8
USP medium for screening material for presence or absence of Salmonella. Selective and differential medium for the isolation, cultivation and differentiation of enteric bacteria, particularly Shigella sp. from both clinical and non-clinical specimens.

Modification of medium developed by Taylor XLD Agar has been shown to be superior to other selective media for the isolation of Shigella. Sodium deoxycholate inhibits Gram positive organisms. Xylose is fermented slowly by Shigella and Providencia and thus demonstrate an alkaline reaction (red colonies). Salmonella ferment xylose rapidly but also decarboxylate lysine giving an alkaline reaction. Excess lactose and sucrose prevent lysine positive organisms from reverting to the alkaline reaction. H2S production by Salmonella and Arizona is indicated by black centered red colonies. Sodium thiosulfate is added as the sulfur source and ferric ammonium citrate as indicator. Phenol red is used as an acid-base indicator with lactose and sucrose fermentation giving yellow colonies (acid reaction).

Directions per Liter: Mix 55.2g per liter of ddH2O until evenly dispersed. Heat with repeated stirring and boil for one minute to dissolve completely. Do not autoclave.

Storage and Stability: Store powdered media at 4C. Opened bottles should be capped tightly and kept in a dark, low humidity environment. Prepared media should be kept at 4C and used within a short period of time.

Appearance: Light pinkish-beige, homogeneous, free flowing powder

Solubiliity: Bright red - reddish orange and clear to trace hazy.

pH: 7.40.2

Important Note: This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.