Salmonella Shigella Agar with Sodium Deoxycholate and Calcium Chloride (SSDC)

Enzymatic digest of casein and meat peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly the B-group. Lactose is the fermentable carbohydrate providing carbon and energy. Sodium citrate, anhydrous sodium thiosulfate and sodium deoxycholate, bile salts and brilliant green are selective agents. Calcium chloride provides trace elements necessary for bacterial growth. Iron (III) citrate is an H₂S indicator. Neutral red is a pH indicator. Bacteriological agar is the solidifying agent.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 76 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. AVOID OVERHEATING. DO NOT AUTOCLAVE. Dispense into appropriate containers.

Instructions for use

1. After the enrichment in Irgasan Ticarcillin Potassium Chlorate Broth (ITC) Base (LC-1361) at 25 °C for 48 hours, inoculate on SSDC plates to obtain well separated colonies.
2. Incubate at 30 °C for 24-48 hours.
3. Characteristic colonies of Yersinia enterocolitica are small (1 mm) and grey with an indistinct rim, non-iridescent and very finely granular when examined with obliquely transmitted light.
4. Confirm 5 of the characteristic or suspicious colonies.
5. If the development of colonies is slow, if coloration is weak, or if there are no characteristic colonies, continue incubation of the plates for up to 48 h, then re-examine them.

• ISO 10273 Microbiology of food and animal feeding stuffs - Horizontal method for the detection of presumptive pathogenic Yersinia enterocolitica.