Principle
- Salmonella Shigella agar is composed of protease peptone, meat extract, lactose, bile salts, sodium citrate, sodium thio-sulfate, ferric citrate, neutral red, brilliant green, and agar.
- Proteose peptone and meat extract provide essential growth nutrients. Lactose is a fermentable carbohydrate. Brilliant green, bile salts, and thiosulphate provide selective and inhibit gram-positive and coliform organisms.
- Certain organisms reduce sodium thiosulphate to sulfite and H2S gas. Sodium thiosulfate and ferric citrate allow the detection of hydrogen sulfide by the production of colonies with black centers.
- Neutral red and brilliant green are present as pH indicators.
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