Description : Triple Sugar Iron Agar (TSI Agar) is used for the differentiation of gram-negative enteric bacilli based on carbohydrate fermentation and the production of hydrogen sulphide. The addition of sucrose increased the sensitivity of the medium by facilitating the detection of sucrose-fermenting bacilli, as well as lactose and/or dextrose fermenters. Carbohydrate fermentation is detected by the presence of gas and a visible colour change (from red to yellow) of the pH indicator, phenol red. The produc