Brilliant Green Agar with Sulfadiazine is used for the selective isolation of Salmonella spp. Peptic digest of animal tissue provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly the B-group. Sucrose and Lactose are fermentable carbohydrates providing carbon and energy. Phenol red is the pH indicator, turning the medium a yellow color with the formation of acid as a result of Lactose/Sucrose fermentation. Brilliant green inhibits Gram positive bacteria and most Gram negative bacilli other than Salmonella spp. Lactose/Sucrose fermenters are usually inhibited. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Sulfadiazine makes the medium more selective. Bacteriological agar is the solidifying agent. When there is a suspicion that the material under study contains low concentrations of Salmonellae, it is necessary to initially inoculate the sample in Brilliant Green Tetrathionate Broth (Cat. 1253) or Selenite Cystine Broth (Cat. 1220) as a preenrichment step. As this medium is very inhibitory it allows for moderately heavy inocula, which should be evenly distributed on the surface of the medium.
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