Cronobacter · Isolation
Chromogenic Cronobacter Agar – blue-green Cronobacter colonies
Chromogenic Cronobacter Agar is a selective and differential agar for the isolation and presumptive identification of Cronobacter spp. after enrichment. Cronobacter forms blue-green colonies on a pale yellow medium.
- Blue-green Cronobacter colonies
- For isolation after selective enrichment
- Easy reading on pale yellow agar
How Chromogenic Cronobacter Agar works
A chromogenic substrate for α-glucosidase, an enzyme typical of Cronobacter, releases a blue-green dye inside the colonies. Selective agents inhibit Gram-positive bacteria, and most other Enterobacteriaceae form colourless or differently coloured colonies.
Typical colony appearance
| Organism | Colonies |
| Cronobacter sakazakii | Blue-green colonies |
| Escherichia coli | Colourless colonies |
| Proteus vulgaris | Grey-black colonies |
| Enterococcus faecalis | Inhibited |
Technical data
| Preparation | 43.1 g/L; boil to dissolve, autoclave 121 °C 15 min, cool to about 50 °C and pour plates |
| Final pH | 7.3 ± 0.2 |
| Incubation | 35–37 °C, 24 h |
| Storage | 2–8 °C, dry and protected from light |
| Shelf life | 2 years |
Applications and practical notes
Cronobacter spp. (formerly Enterobacter sakazakii) can cause severe infections in newborns, so powdered infant formula and its production environment are tested according to ISO 22964. Typical applications include:
- Powdered infant formula and follow-on formula
- Infant cereals and milk powders
- Environmental samples from dry production areas
- Ingredients for infant foods
Working with Chromogenic Cronobacter Agar: Incubate the plates at 35–37 °C for 24 hours and confirm typical blue-green colonies biochemically.
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 Cronobacter method: ISO 22964 is the horizontal method for Cronobacter spp. in infant formula, infant cereals, milk powders and production environments. It combines pre-enrichment in Buffered Peptone Water, selective enrichment at 41.5 °C, plating on a chromogenic agar and biochemical confirmation; the FDA BAM Chapter 29 uses a similar culture and PCR approach. COLO.Science offers media, supplements, rapid tests and identification kits 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 Cronobacter 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 Cronobacter Agar, please send us a request. With every delivery of Chromogenic Cronobacter Agar you receive the lot number and expiry date, and on request we send the available documentation for Chromogenic Cronobacter Agar.
Where Chromogenic Cronobacter Agar fits in Cronobacter testing
- Pre-enrichment – Buffered Peptone Water, 34–38 °C
- Selective enrichment – Cronobacter enrichment broth with vancomycin-type supplement at 41.5 °C
- Isolation – Chromogenic Cronobacter Agar: blue-green colonies
- Confirmation – biochemical identification; rapid screening by qPCR, LAMP or detection plate
See all Cronobacter products in the Microbiology Catalogue →
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Chromogenic Cronobacter Agar | PRO7584 | 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.
