Staphylococcus aureus · Chromogenic agar
Chromogenic Staphylococcus aureus Agar – direct colour identification
Chromogenic Staphylococcus aureus Agar is a selective medium on which S. aureus forms pink to purple-red colonies. The colour reaction separates it from other staphylococci and makes reading faster than on conventional agars.
- Pink to purple-red colonies for S. aureus
- Other staphylococci blue or colourless
- No autoclaving – heat to boiling only
How Chromogenic Staphylococcus aureus Agar works
A chromogenic substrate is split by an enzyme specific for S. aureus, and the released dye colours the colonies pink to purple-red. Selective agents suppress Gram-negative bacteria and many other Gram-positive organisms. S. saprophyticus forms blue or blue-green colonies.
Typical colony appearance
| Organism | Colonies |
| S. aureus | Pink to purple-red colonies with regular edges |
| S. saprophyticus | Blue to blue-green colonies |
| E. faecalis, B. subtilis | Inhibited |
Technical data
| Preparation | 67.4 g/L; heat to boiling until dissolved, cool to about 50 °C, mix and pour plates (no autoclaving) |
| Final pH | 6.9 ± 0.2 |
| Incubation | 35–37 °C, 18–24 h |
| Storage | 2–8 °C, dry and protected from light; keep the bottle tightly closed |
| Shelf life | 2 years |
Applications and practical notes
Selective and differential agars for Staphylococcus aureus and other coagulase-positive staphylococci are used in food, feed, cosmetics and pharmaceutical testing, for example according to ISO 6888-1 and FDA BAM Chapter 12. Typical applications include:
- Enumeration of coagulase-positive staphylococci in food and feed
- Testing of dairy products, meat, ready meals and confectionery
- Microbial limit tests of non-sterile pharmaceutical and cosmetic products
- Hygiene monitoring of food handlers and surfaces
Working with Chromogenic Staphylococcus aureus Agar: Protect the prepared plates from light and use them within a few days, because the chromogenic substrate is light-sensitive.
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 Staphylococcus aureus methods: coagulase-positive staphylococci in the food chain are counted on Baird-Parker Agar according to ISO 6888-1, and typical colonies are confirmed with the coagulase test. For low numbers, ISO 6888-3 uses an MPN technique with Giolitti-Cantoni Broth, and the FDA BAM Chapter 12 describes direct plating and an MPN method with Tryptic Soy Broth containing 10 % NaCl. In pharmaceutical microbiology, the test for S. aureus in EP 2.6.13 and USP <62> uses Mannitol Salt Agar. COLO.Science offers media, supplements, rapid tests, identification kits and QC strains for every step.
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 Staphylococcus aureus 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 Staphylococcus aureus Agar, please send us a request. With every delivery of Chromogenic Staphylococcus aureus Agar you receive the lot number and expiry date, and on request we send the available documentation for Chromogenic Staphylococcus aureus Agar.
Where Chromogenic Staphylococcus aureus Agar fits in Staphylococcus aureus testing
- Colony count – Baird-Parker Agar with Egg Yolk Tellurite Emulsion (ISO 6888-1); alternatives: chromogenic S. aureus agar or Vogel-Johnson Agar
- Low numbers (MPN) – Giolitti-Cantoni Broth (ISO 6888-3) or Tryptic Soy Broth with 10 % NaCl (FDA BAM), then plating on Baird-Parker Agar
- Confirmation – coagulase test with Rabbit Plasma, latex kit or DNase Agar
- Pharmaceutical products – Mannitol Salt Agar for the S. aureus test of EP 2.6.13 / USP <62>; QC strains for media testing
See the complete Staphylococcus set in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Chromogenic Staphylococcus aureus Agar | PRO7589 | 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.
