Acetate Differential Agar, Modified 500G

Acetate Differential Agar, Modified medium is recommended for the differentiation of Shigella species from Escherichia coli in accordance with FDA BAM, 1998. Acetate utilization is indicated by formation of blue colour, which is due to the utilization of sodium acetate and subsequent formation of an alkaline reaction detected by the presence of bromothymol blue indicator. Shigella does not utilize acetate , hence is negative and do not show blue colouration, whereas E.coli shows positive reaction.