This is a selective medium for the isolation of Salmonella spp. and Shigella spp. from clinical specimens and food samples.
SS agar is a modification of the original DCA medium described by Leifson. The formulation for SS agar was later modified to improve the growth of Shigella spp.
SS agar modified differs from SS agar in that it has an alternation to the bile salts mixture, peptone, pH value, and total g/litre.
The peptone provides the required carbon, nitrogen and vitamins. Lactose is a fermentable carbohydrate and neutral red is a pH indicator.
Sodium thiosulphate and ferric citrate are used to detect hydrogen sulphide production indicated by the black centred colonies of hydrogen sulphite positive organisms.
Bile salts, sodium citrate and brilliant green inhibit Gram-positive bacteria and a number of different coliform bacteria.
Salmonella Shigella (SS) Agar Modified
Additional Information
| Container | |
|---|---|
| Shelf Life (days) | |
| Storage Temp (°C) | |
| Dehydrated Medium Appearance | |
| Prepared Medium Appearance | |
| Dehydrated Medium Colour | |
| Prepared Medium Colour | |
| Dehydrated PH | |
| Prepared PH | |
| Recommended Incubation |
Product Description
| Organisms | Ref. No | Result |
| Salmonella enteritidis | NCTC 12694 | Growth, translucent colonies with black centre |
| Shigella sonnei | NCTC 8574 | Growth, pale pink/yellow colonies |
| Enterococcus faecalis | NCTC 12697 | Inhibited |
Formula*
| g/L | |
| Peptone | 10.0 |
| Lactose | 10.0 |
| Bile salts | 5.5 |
| Sodium citrate | 10.0 |
| Sodium thiosulphate | 8.5 |
| Ferric citrate | 1.0 |
| Brilliant green | 0.00033 |
| Neutral red | 0.025 |
| Agar | 12.0 |
| Total | 57.0 |
| *Adjusted/supplemented as required to meet performance requirements |
Preparation
Suspend 57g of the medium in one litre of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes. Heat with frequent agitation and boil for one minute to completely dissolve the medium. DO NOT AUTOCLAVE this medium. Cool to 45-50°C and aseptically dispense into appropriate sterile containers.