DIAGNOSTIC STUART’S UREA BROTH BASE (UREA BROTH BASE)

Rustigian and Stuart developed Urea Broth. This medium is especially recommended for the differentiation of Proteus species from Salmonella and Shigella species in the enteric infection diagnosis, based on urea utilization. Gram-negative enteric bacilli are unable to utilize urea because of less nutrients and high buffering capacity of the medium. Urea Broth becomes alkaline as the utilization of urea by the organisms liberates ammonia during the incubation, indicated by pink red colour. All urea test media rely on the alkalinity formation and so they are not specific for urease testing. The utilization of proteins may raise the pH to alkalinity due to protein hydrolysis and excess of amino acids results in false positive reaction. A medium without urea serves as negative control to rule out false positive results.

a general-purpose medium for the cultivation of microorganisms, especially obligate anaerobes