Shigella · Selective isolation
Chromogenic Shigella Agar – selective chromogenic medium for Shigella
Chromogenic Shigella Agar is a selective medium for the isolation and presumptive identification of Shigella from food, water and stool samples. It is completed with the Chromogenic Shigella Agar Supplement.
- Chromogenic differentiation of Shigella
- Completed with the selective supplement
- Accompanying flora inhibited
How Chromogenic Shigella Agar works
Selective agents inhibit Gram-positive bacteria and much of the accompanying flora. Shigella forms white to pink colonies and turns the surrounding medium red, while E. coli forms yellow colonies with a clear halo.
Typical colony appearance
| Organism | Colonies |
| Shigella spp. | White to pink colonies, medium around them red |
| Escherichia coli | Yellow colonies with clear halo |
| Staphylococcus aureus | Inhibited |
Technical data
| Preparation | 51.2 g/L; boil with stirring until dissolved; do not autoclave; cool to 50–55 °C and add the supplement dissolved in 30 mL water to 970 mL of base |
| Final pH | 6.8 ± 0.2 |
| Incubation | 37 °C, 22–24 h |
| Storage | 2–8 °C, dry, protected from light |
| Shelf life | 2 years |
Applications and practical notes
Shigella causes bacillary dysentery and is tested in food, water and clinical samples, for example according to ISO 21567. Typical applications include:
- Ready-to-eat foods, salads and vegetables
- Seafood and dairy products
- Drinking and surface water
- Clinical and public-health laboratories
Working with Chromogenic Shigella Agar: Heat the base only until dissolved, do not autoclave, and add the filter-sterilised supplement at 50–55 °C.
Good practice with dehydrated media: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About the Shigella and Yersinia methods: ISO 21567 describes the detection of Shigella in food by enrichment in Shigella broth with novobiocin, plating on selective agars such as MacConkey, XLD and Hektoen enteric agar, and biochemical and serological confirmation. ISO 10273 describes the detection of presumptive pathogenic Yersinia enterocolitica by enrichment at 25 °C and plating on CIN agar, followed by tests that separate pathogenic from non-pathogenic strains. COLO.Science offers media, supplements, rapid tests, identification kits and QC strains for these methods.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
Chromogenic Shigella Agar is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Chromogenic Shigella Agar, please send us a request. With every delivery of Chromogenic Shigella Agar you receive the lot number and expiry date, and on request we send the available documentation for Chromogenic Shigella Agar.
Where Chromogenic Shigella Agar fits in Shigella and Yersinia testing
- Enrichment – Shigella broth with selective supplement; for Yersinia a peptone-sorbitol-bile type broth
- Selective isolation – Chromogenic Shigella Agar, Desoxycholate Citrate Agar, XLD; for Yersinia CIN agar and Chromogenic Yersinia enterocolitica Agar
- Screening – qPCR or LAMP kits after enrichment
- Confirmation and QC – biochemical identification kits and reference strains
See all Shigella and Yersinia products in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Chromogenic Shigella Agar | PRO7588 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
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Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
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Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
