Liofilchem® Chromatic™ Cronobacter Isolation Agar

Liofilchem® Chromatic™ Cronobacter Isolation Agar (CCI) is a chromogenic selective medium developed for the isolation and differentiation of Cronobacter species (formerly Enterobacter sakazakii) from food, animal feed, and environmental samples within food production and handling facilities.

The formulation complies with ISO 22964:2017, which prescribes its use in combination with Cronobacter Selective Broth (CSB, ref. 24483) for confirmatory detection. The medium enables rapid and specific identification of Cronobacter spp. by producing blue to blue-green colonies, ensuring efficient monitoring of this opportunistic foodborne pathogen in accordance with ISO and EN standards.

Key Features

• ISO 22964-compliant for Cronobacter spp. detection and isolation.
• Chromogenic differentiation—distinct Cronobacter colonies appear blue to blue-green.
• Suppresses Gram-positive flora via sodium desoxycholate.
• Differentiates hydrogen sulfide producers among Enterobacteriaceae.
• Optimized for confirmatory streaking following CSB enrichment.
• Supports pre-enrichment workflow with Buffered Peptone Water and Cronobacter Selective Broth.
• Accurate colony color differentiation within 24 ± 2 hours.

Typical Formula (per litre)

Principle of the Method

• Tryptic digest of casein and yeast extract provide essential growth nutrients, including amino acids, nitrogen, and vitamins.
• Sodium chloride maintains osmotic equilibrium, while phosphates stabilize pH.
• 5-Bromo-4-chloro-3-indoxyl-α-D-glucopyranoside serves as the chromogenic substrate for detecting the α-glucosidase activity of Cronobacter spp., producing blue to blue-green colonies.
• Sodium desoxycholate acts as a selective agent against Gram-positive bacteria.
• Ammonium iron citrate and sodium thiosulfate differentiate hydrogen sulfide-producing Enterobacteriaceae, which appear gray or black.

Preparation

1. Suspend 32.4 g of powder in 1 L of distilled or deionized water.
2. Heat gently while stirring until fully dissolved.
3. Autoclave at 121°C for 15 minutes.
4. Cool to 45–50°C and pour aseptically into Petri dishes.

Test Procedure (According to ISO 22964:2017)

1. Pre-enrich 10 g/mL of the sample in Buffered Peptone Water (ref. 414030) at 36 ± 2°C for 18 ± 2 hours.
2. Transfer 0.1 mL of pre-enrichment culture into Cronobacter Selective Broth (CSB, ref. 24483) and incubate at 41.5°C for 24 ± 2 hours.
3. Select tubes showing yellow coloration and streak onto Chromatic™ Cronobacter Isolation Agar (CCI).
4. Incubate at 41.5°C for 24 ± 2 hours.
5. Observe for characteristic blue to blue-green colonies (1–3 mm).

Interpretation of Results

Confirm suspected colonies by streaking on Tryptic Soy Agar (ref. 10037) and incubating at 36 ± 2°C for 21 ± 3 hours per ISO 22964 confirmation procedures.

Quality Control

Incubation: 41.5 ± 1°C for 24 ± 2 hours.

Dehydrated Appearance: yellowish, free-flowing powder.

Prepared Medium: slightly opalescent, light amber.

Storage and Stability

• Store dehydrated medium at 10–30°C in a dry, tightly sealed container.
• Store prepared plates at 2–8°C, away from light.
• Shelf life:
  • Dehydrated medium – 4 years
  • Ready-to-use plates – 6 months

Safety and Handling

• For in vitro diagnostic use only.
• Handle samples under biosafety level 2 (BSL-2) conditions.
• Use by trained laboratory professionals following aseptic techniques.
• Refer to the Safety Data Sheet (SDS) for proper handling.
• Dispose of waste according to local and national regulations.

Ordering Information

Liofilchem® Chromatic™ Cronobacter Isolation Agar (CCI) offers a rapid, specific, and ISO-compliant chromogenic method for the detection of Cronobacter spp. from food, feed, and environmental samples. When used with Cronobacter Selective Broth, it delivers precise and reproducible results for food safety, infant formula, and environmental hygiene testing, supporting laboratories in compliance with ISO 22964:2017 standards.