XLD Agar EP, USP, JP formulation is a selective medium used for isolating and differentiating Gram-negative enteric bacilli, particularly Shigella spp./ Providencia spp. and Salmonella spp. according to Harmonized EP, USP, JP.

Differentiation of Salmonella spp. and Shigella spp./ Providencia spp. from non-pathogenic bacteria is accomplished by three reactions: xylose fermentation, lysine decarboxylation and hydrogen sulphide production:

• Degradation of xylose, lactose and sucrose generates acid production, causing the medium turns from red to yellow.
• Hydrogen sulphide production is inhibited if the pH is low, while causes the formation of colonies with black center under alkaline conditions.

Lysine decarboxylation, in the absence of lactose and sucrose fermentation, results in a reversion to alkaline conditions, causing the medium turns back to red.

Salmonella spp. produces red colonies with black centers.

Shigella spp. and Providencia spp. produce red colonies.

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Ref. 10413
20 plates/pack
10-25°C storage temperature
6 months shelf life

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