UREA INDOLE MEDIUM

Urea Indole Medium is a differential medium for the identification of Enterobacteriaceae based on the ability of the bacteria to hydrolyze urea and produce indole. This is particularly useful when differentiating between Proteus species and organisms like Salmonella and Shigella during microbiological examinations.
It contains L-tryptophan which is a substrate for indole production. Microorganisms that have the enzyme tryptophanase convert tryptophan to indole, which can be detected with Kovacs reagent. Urease activity is measured using urea as substrate. Urease-producing microorganisms hydrolyze urea and liberate ammonia which increases the alkalinity of the medium. Phenol red indicates this reaction through a visible colour change, with a pink colour indicating urease activity.
Sodium chloride maintains osmotic balance and phosphate salts provide buffering capacity. The medium provides the convenience of two complementary biochemical reactions in one format, which is useful for presumptive identification and differentiation of Enterobacteriaceae in clinical microbiology laboratories.

A differential medium for identifying Enterobacteriaceae through urease activity and indole production, helping distinguish organisms such as Proteus from Salmonella and Shigella.