Edwardsiella ictaluri medium is a selective medium for the isolation of Edwardsiella spp. Based on the formulation by Shotts et al. Edwardsiella spp. may be differentiated from other microorganisms on this medium due to its colony morphology.

The peptones provide the required carbon, nitrogen and vitamins. Sodium chloride maintains the osmotic balance. Colistin and bile salts are selective agents to inhibit most Gram-negative and Gram-positive organisms. Mannitol is a fermentable carbohydrate and bromthymol blue is a pH indicator. Phenylalanine and ferric citrate are used to detect phenylalanine deaminase activity in Proteus spp. Agar is a solidifying agent.

Shotts et al. noted Proteus spp. swarming can overgrow on a mixed cultured sample. Therefore, a selective supplement (LS0021) may be added to the medium to restrict Proteus spp. swarming

Preparation

Suspend 45g of the medium in 1L of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes. Sterilise at 121°C for 15 minutes with frequent agitation. Cool to 45- 50°C. Mix well and aseptically dispense into appropriate sterile containers.