E and O Labs Edwardsiella ictaluri Medium

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.

• Storage conditions: 10 to 30°C
• Dehydrated medium appearance: fine powder
• Dehydrated medium colour: straw
• Prepared medium appearance: firm gel
• Prepared medium colour: green
• pH: 7.1 ± 0.2
• Recommended incubation: aerobically at 30°C ± 2°C for 24 to 48 hours
• *Shotts et al. noted Proteus spp. swarming can overgrow on a mixed cultured sample, therefore, a selective supplement may be added to the medium to restrict Proteus spp. swarming