![]() ![]() STORAGE AND SHELF LIFE Storage: Upon receipt store at 2-8 degrees C. * Adjusted and/or supplemented as required to meet performance criteria. FORMULA Ingredients per liter of deionized water:* Lactose 7.5gm Sucrose 7.5gm Sodium Thiosulfate 6.8gm L-Lysine 5.0gm Sodium Chloride 5.0gm Xylose 3.75gm Yeast Extract 3.0gm Sodium Deoxycholate 2.5gm Ferric Ammonium Citrate 0.8gm Phenol Red 0.08gm Agar 15.0gm Final pH 7.4 +/- 0.2 at 25 degrees C. Examples of such organisms are Citrobacter spp., Proteus spp., and Escherichia coli. Organisms which ferment xylose, are lysine decarboxylase-negative, and do not ferment lactose or sucrose cause an acid pH in the medium, and form yellow colonies. The addition of sodium thiosulfate and ferric ammonium citrate as a sulfur source and indicator, respectively, allows hydrogen sulfide forming organisms to produce colonies with black centers, under alkaline conditions. To avoid this reversal to a Shigella reaction, lactose and sucrose are added in excess. Lysine decarboxylation reverts the pH of the medium to an alkaline condition. A second differential mechanism for Salmonella is employed by the addition of lysine. The carbohydrate source is xylose which is fermented by most enterics except for Shigella species, and these colonies appear red on this medium as a result. The selective agent in XLD Agar is sodium deoxycholate, which inhibits the growth of gram-positive organisms. It has also been found to be an excellent medium for isolating Salmonella species as well. SUMMARY Xylose Lysine Deoxycholate (XLD) Agar was developed by Taylor for the differentiation, isolation, and identification of enteric pathogens, and to support the growth of more fastidious enteric organisms.(6) XLD Agar was especially designed to allow the growth of Shigella species, and is a proven medium for the isolation of this organism. G65 XLD Agar, 15x100mm Plate, 18ml 10 plates/bag INTENDED USE Hardy Diagnostics XLD Agar is recommended for use as a selective and differential medium for the isolation of gram-negative enteric pathogens from fecal and other specimens. ![]()
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