Isolation of enteric bacilli and differentiation of lactose fermenters. Description: Deoxycholate Agar was first described by Leifson for the isolation of intestinal pathogens and for the enumeration of colon bacilli in milk and water. In the microbiological analysis of dairy products and water, Deoxycholate Agar is normally used for enumeration of conforms in pour plates. It may also be used for isolation of enteric pathogens by surface inoculation from rectal swabs, feces or other specimens. Deoxycholate Agar should be used in parallel with other plating media when used for this purpose. Sodium deoxycholate and sodium citrate are incorporated in the medium to inhibit the growth of Gram positive organisms. Fermentation of lactose causes an acid reaction in the medium resulting in the formation of deep red colonies.