Leifsons Deoxycholate Agar, Modified, 5KG

Leifson Deoxycholate Agar, was originally described by Leifson and further modified by Hynes for selective isolation and differentiation of Salmonella and Shigella species. This medium is the modification of Leifson Agar for the isolation and maximum recovery of intestinal pathogens. Leifson Deoxycholate Agar, Modified is a less selective medium and is used for direct sampling of faeces. Peptic digest of animal tissue and beef extract provide essential growth nutrients. Sodium citrate and sodium deoxycholate inhibit all gram-positive bacteria and coliforms but allow the gram-negative bacilli to grow. Lactose is added to the medium to allow differentiation of lactose fermenting bacteria such as, Escherichia coli from non-lactose fermenting species, such as Salmonella , Proteus and Shigella . Lactose fermenting strains grow as red to pink colonies because of absorption of neutral red indicator. Nonfermenting species grow as colourless colonies. Ferric citrate and sodium thiosulphate help in H2S determination. Storage and Shelf-life: Store below 30°C in tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label.