Triple Sugar Iron Agar 500gm Himedia is Recommended for the identification of gram-negative enteric bacilli based on dextrose, lactose, and sucrose fermentation and hydrogen sulfide production. Originally proposed by Sulkin and Willett and modified by Hajna for identifying Enterobacteriaceae. This medium complies with the recommendation of APHA, for the examination of meat and food products, for the examination of milk and dairy products, and for microbial limit tests for confirming the presence of Salmonellae and in the identification of gram-negative bacilli. The reactions can be interpreted as follows: Alkaline slant/acid butt- only glucose fermented, Acid slant/acid butt- dextrose and sucrose fermented or dextrose and lactose fermented or all the three sugars, dextrose, lactose and sucrose fermented, Bubbles or cracks present-gas production Black precipitate present-H2S gas production.