Salmonella Shigella (SS) Agar Modified

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.

Selective medium for the isolation of Salmonella spp. and Shigella spp. from clinical specimens and food samples

Shelf Life (days): 1095 days

Storage Temp (°C): 10-30°C

Dehydrated Medium Appearance: Fine Powder

Prepared Medium Appearance: Firm Gel

Dehydrated Medium Colour: Beige

Prepared Medium Colour: Pale Orange

Dehydrated PH: 7.3 ± 0.2

Prepared PH: 7.3 ± 0.2

Recommended Incubation: Aerobically at 37°C ± 1°C for 18-24 hours

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

Shelf Life (days)	1095 days
Storage Temp (°C)	10-30°C
Dehydrated Medium Appearance	Fine Powder
Prepared Medium Appearance	Firm Gel
Dehydrated Medium Colour	Beige
Prepared Medium Colour	Pale Orange
Dehydrated PH	7.3 ± 0.2
Prepared PH	7.3 ± 0.2
Recommended Incubation	Aerobically at 37°C ± 1°C for 18-24 hours