Description
Selective and differential medium for isolation of Salmonella and some shigella strains from clinical and food materials.
Salmonella Shigella Agar is a selective differential agar medium used for isolation of pathogenic Enterobacteriaceae, specifically Salmonella sp. and Shigella sp. from foods, other sanitary materials and clinical specimens. Early studies, indicated that SS Agar was superior to other media in the isolation of Salmonella and Shigella from specimens. Later investigators, determined that SS Agar was inferior to Hektoen Enteric Agar and XLD Agar in the recovery of Shigella. Inhibitory action on coliforms and Gram-positive bacteria is obtained by the bile salts mixture and brilliant green in the medium. Sodium citrate inhibits Gram-positive bacteria. Neutral red is a pH indicator and those bacteria which ferment lactose produce pink colonies. Some Salmonella and Proteus sp. produce black-centered (precipitated ferrous sulfate) colonies as a result