AGAR MEDIUM J (DEOXYCHOLATE CITRATE AGAR) (as per BP/EP/IP)

Description

Deoxycholate Citrate Agar Medium is prepared as per the modified formula of Leifson and is also recommended as per British Pharmacopoeia and is also designated as Agar medium J. This medium is used for the isolation and maximum recovery of intestinal pathogens belonging to Salmonella and Shigella groups from foods and pharmaceutical products. However, it is recommended to use less inhibitory medium when Shigella have to be isolated. Salmonella major causative agent of enteric disease especially food borne toxic infection and typhoid was first observed by Eberth in 1880. This medium is routinely used to check the presence of Salmonella contamination in food and pharmaceutical products as per BP. Sodium deoxycholate at pH 7.3 to 7.5 is inhibitory for gram-positive bacteria. Proteus and other Gram positive organisms are also inhibited due to higher concentration of both citrate and deoxycholate salts in this medium. The reduction of ferric citrate to iron sulphide by H2S gives the indicative appearance of colonies with black center. Citrate salt, in the concentration included in the formulation, are inhibitory to gram-positive bacteria and most other normal intestinal organisms.