The TSI slant is a test tube that contains agar, a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose,[REF] as well as sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate.
TSI agar medium was developed based on Kligler's iron agar, which had been used for the determination of lactose fermentative bacteria, by addition of sucrose to be able to detect sucrose fermentative bacteria also.