Liofilchem® Chromatic™ CRE Agar Base

Liofilchem® Chromatic™ CRE Agar Base is a chromogenic and selective medium designed for the isolation and differentiation of carbapenem-resistant Enterobacteriaceae (CRE) directly from clinical samples, such as rectal swabs and stool specimens.

When supplemented with Chromatic™ CRE Supplement (ref. 81088), this medium facilitates rapid and reliable detection of carbapenemase-producing organisms (CPOs) including Klebsiella pneumoniae, Escherichia coli, Enterobacter spp., Serratia spp., and Citrobacter freundii.

By differentiating species based on colony color and morphology, Chromatic™ CRE Agar Base supports effective infection control, outbreak monitoring, and antimicrobial resistance (AMR) surveillance programs in clinical and public health laboratories.

Key Features

• Chromogenic, selective medium for detection of carbapenem-resistant Enterobacteriaceae (CRE).
• Distinct colony colors for presumptive differentiation of Klebsiella, E. coli, Enterobacter, and Citrobacter.
• Used with Chromatic™ CRE Supplement (ref. 81088) for optimal selectivity.
• Rapid results within 18–24 hours under aerobic incubation.
• Detects carbapenemase-producing KPC, NDM, OXA, VIM strains.
• Complies with EUCAST and CLSI recommendations.
• Ideal for clinical, hospital, and infection control microbiology testing.

Typical Formula (per litre)

Principle of the Method

• Peptone mix provides essential nitrogen, carbon, vitamins, and minerals to support Enterobacteriaceae growth.
• The chromogenic and selective mix differentiates CRE based on enzyme activity and colony color.
• Agar solidifies the medium and allows for easy colony observation.
• When enriched with Chromatic™ CRE Supplement, the medium suppresses carbapenem-sensitive and non-Enterobacteriaceae species, ensuring high selectivity.

Carbapenemase-producing organisms are identified by their distinct colony colors, which correlate with species and enzyme activity, facilitating presumptive identification and resistance screening.

Preparation

1. Suspend 56.8 g of powder in 1 L of deionized or distilled water.
2. Heat and stir until fully dissolved, then autoclave at 121°C for 15 minutes.
3. Cool to 45–50°C.
4. Add 2 vials (10 mL) of reconstituted Chromatic™ CRE Supplement (ref. 81088).
5. Mix well and pour into sterile Petri dishes.

Technique

1. Inoculate directly from rectal or fecal screening swabs or from a liquid suspension of the sample.
2. Incubate aerobically at 37°C for 18–24 hours.
3. Observe for colony color and morphology for presumptive identification.

Interpretation of Results

Quality Control

Incubation: 18–24 h at 35 ± 2°C (aerobic).

Appearance (Dehydrated): fine, beige powder.

Appearance (Prepared): slightly opalescent, amber.

Storage and Stability

• Store dehydrated medium at 10–30°C in a dry, sealed container.
• Store prepared plates at 2–8°C, protected from light.
• Shelf life: 2 years (dehydrated).
• Discard if contaminated, clumped, or discolored.

Safety and Handling

• For in vitro diagnostic use only.
• Handle all samples and cultures under appropriate biosafety level 2 precautions.
• Use by trained laboratory personnel following aseptic techniques.
• Consult the Safety Data Sheet (SDS) before handling.
• Dispose of used materials per institutional and local biosafety regulations.

Ordering Information

Liofilchem® Chromatic™ CRE Agar Base, when used with Chromatic™ CRE Supplement, provides a highly selective chromogenic platform for the detection and differentiation of carbapenem-resistant Enterobacteriaceae. Its clear color-based identification system supports rapid screening, infection control, and antimicrobial resistance surveillance, making it an essential tool for clinical, hospital, and reference microbiology laboratories.