BacterPlate™ XLD Agar

INTENDED USE

BacterPlate™ XLD Agar is used for the isolation of Salmonella in pharmaceutical products. It can also be used as a second media of choice in the normalized methods for the detection of Salmonella in food products and water.
The packaging with semi-permeable Cellophane film helps balance the humidity of the environment during storage.

PRINCIPLE

Sodium desoxycholate inhibits contaminating Gram-positive flora. Xylose is fermented by practically all enteropathogenic bacteria, except for Shigella which are thus differentiated from the other species. After exhausting xylose, Salmonella decarboxylate lysine (via lysine decarboxylase) to cadaverine, causing the pH to rise. Colonies of salmonellae resemble those of shigellae in the medium having become basic. The colonies formed are red in the presence of the indicator, phenol red.
The addition of lactose and sucrose to the medium enable coliform bacteria to decarboxylate lysine and thereby produce excess acidity, making the indicator turn yellow, favoring their differentiation.
In basic medium, pathogenic H₂S-producers reduce ferric ammonium citrate and cause a blackening due to the production of iron sulfide at the center of the colonies. Non-pathogenic bacteria which do not decarboxylate lysine acidify the medium, a result of sugar fermentation. The pH decrease prevents the colonies from blackening.

Note: For using XLD Agar as the second Salmonella isolation media, incubate the plates 24 hours at 37 °C.

RESULTS

Microorganisms	Characteristics
Escherichia coli, Citrobacter, Enterobacter, Proteus, Serratia, Klebsiella	Yellow colonies, with or without a black center
Shigella, Providencia, Salmonella Paratyphi A	Red colonies without black center
Salmonella, Edwardsiella	Red colonies with black center

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference strains	Incubation Conditions	Expected results
E. faecalis ATCC 29212	35 ± 2^oC for 18 – 24 hours	Inhibited, no growth
E.coli ATCC 35218		Weak growth, yellow colonies
S. Enteritidis ATCC 13076		Good growth, red colonies with black centers

For 1 liter of medium

pH of the ready-to-use medium at 25⁰C: 7,4 ± 0,2

*Note: This ingredient is for reference only our company will formulate the ingredient according to requests or tender specifications.

Product Name	Code	Packaging
BacterPlate™ XLD Agar	05043	10 plates/ box or as per customer request.