Triple Sugar Iron Agar is used (TSI Agar)for confirmation of gram negative enteric bacilli on basis of dextrose, lactose and sucrose fermentation and H2S production or confirmation of gram negative enteric bacilli on basis of dextrose, lactose and sucrose fermentation and H2S production. It is recommended by BIS committee under specification IS:5887 (Part I, III and V) 1976, reaffirmed 2005. (TSI Agar)Triple Sugar Iron Agar was originally proposed by Sulkin and Willet and modified by Hajna for identifying Enterobacteriaceae. ISO Committee and BIS has recommended a slight modification for the identification of Salmonellae. BIS has recommended the medium for detection of Escherichia coli and Vibrios. (TSI Agar)Triple Sugar Iron Agar is recommended for confirmation of gram negative bacilli on basis of dextrose, lactose and sucrose fermentation and H2S production. The ingredients included in the medium such as peptone, yeast extract, meat extract provide the nitrogen, carbon, and vitamins required for organism growth. Triple sugar Iron Agar Consists of three carbohydrates-dextrose, Lactose and Sucrose. When the carbohydrate are fermented, acid production is detected by the phenol red pH indicator. Sodium thiosulphate is reduced to hydrogen sulphide, and hydrogen sulphide reacts with an iron salt yielding the typical black iron sulphide. Ferric ammonium citrate is the hydrogen sulphide (H2S) indicator. Sodium chloride maintains the osmotic balance of the medium. Agar is used as a solidifying agent.