SS Agar is a high-quality selective medium specifically designed for the isolation of Salmonella spp and some strains of Shigella spp from clinical samples and other contaminated materials. Thanks to its unique formulation, SS Agar is particularly effective in the primary isolation of Salmonella from heavily contaminated samples, making it an essential tool for microbiology laboratories and food safety control.

Product Features

• Format: Pack of 20 90 mm plates


• Application: Isolation of Salmonella spp and Shigella spp


• Use: Ideal for contaminated clinical and food samples


• Recommendations: Complies with APHA guidelines for food examination

Medium Composition

The typical SS Agar formula includes the following components per liter:

• Pancreatic Digest of Casein: 2.5 g


• Peptic Digest of Animal Tissue: 2.5 g


• Beef Extract: 5.0 g


• Lactose: 10.0 g


• Sodium Thiosulfate: 8.5 g


• Sodium Citrate: 8.5 g


• Bile Salts: 8.5 g


• Ferric Ammonium Citrate: 1.0 g


• Brilliant Green: 0.00033 g


• Neutral Red: 0.025 g


• Agar: 15.0 g


• Final pH: 7.0 ± 0.2 at 25°C

Method Principle

The working principle of SS Agar is based on a combination of nutrients and inhibitors that promote the growth of Salmonella and inhibit Gram-positive bacteria and many Enterobacteriaceae. Here is how it works:

• Nutrients: The pancreatic digest of casein, the peptic digest of animal tissue, and the beef extract provide amino acids, nitrogen, carbon, vitamins, and minerals necessary for microbial growth.


• Fermentable carbohydrate: Lactose is used as a fermentable energy source.


• Inhibition: Bile salts, sodium citrate, and brilliant green inhibit unwanted bacteria, allowing selective growth of Salmonella and Shigella.


• Production indicators: Sodium thiosulfate and ferric ammonium citrate allow detection of hydrogen sulfide production, indicated by the formation of colonies with black centers.


• pH indicators: Neutral red acts as a pH indicator, while agar serves as the solidifying agent for the medium.

Conclusion

SS Agar is an ideal choice for laboratories that need a reliable medium for the isolation of Salmonella spp and Shigella spp. Its balanced formulation and selective properties make it an indispensable product for ensuring food safety and public health.