Bile salts selective detection

Dissociated jaundice (ictere dissociee) refers to a dissociation of bilirubin and bile salt excretion in which bilirubin is retained, leading to jaundice, but bile salts are excreted in a normal manner so that such patients are icteric but do not have pruritus and no bile salts are detected in blood or urine. The concept was held that only the hepatic cell could selectively retain bilirubin but excrete bile salts and that bile ducts or gallbladder cells could not. The observation of dissociated jaundice was therefore regarded as useful in distinguishing jaundice due to hepatitis or cirrhosis from that caused by bile duct obstruction (74-76). 

Selective-differential media some media have both properties, e.g., MacConkey agar. It is selective as it contains crystal violet and bile salts which inhibit the growth of bacteria other than coliforms. It is differential as it contains neutral red and lactose, which is degraded by coliforms to acid and is detected due to a change in pH. At acidic pH, colourless neutral red becomes red and the colonies develop a red colour. Shigella and Salmonella colonies remain colourless and therefore can be easily distinguished [9,11]. 

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