Cetrimide Agar Base
Also known as：Cetrimide Agar · Cetrimide Selective Agar · Pseudomonas Cetrimide Agar
For the selective isolation and identification of Pseudomonas aeruginosa, following the addition of glycerol, in accordance with the harmonized pharmacopoeias.
- Category
- Dehydrated Culture Media
- Dissolve per litre
- 46.7 g
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- ISO 22000
Data updated：2026-11-07
Brand cross-reference：BD Difco Pseudosel Agar · Oxoid Pseudomonas Cetrimide Agar · Merck Cetrimide Agar（USP <62>、EP 2.6.13） Brand cross-reference
Overview
Cetrimide Agar Base is the standard selective medium for Pseudomonas aeruginosa, specified in pharmacopoeial microbial limit tests. Cetrimide suppresses most other bacteria, while potassium sulfate and magnesium chloride stimulate the green and blue pigments of P. aeruginosa, fluorescent under UV light. Used to test pharmaceuticals, cosmetics and water for P. aeruginosa.
Principle
Cetrimide Agar is based on the selective medium of Brown and Lowbury for the isolation of Pseudomonas aeruginosa.¹ Pancreatic digest of gelatin supplies nitrogen, amino acids, and growth factors, and glycerol serves as the carbon and energy source. Cetrimide, a quaternary ammonium compound, acts as a detergent that inhibits most bacteria other than Pseudomonas aeruginosa. Magnesium chloride and potassium sulphate enhance the production of the pigments pyocyanin and fluorescein. Pseudomonas aeruginosa forms colonies with a yellow-green to blue-green pigment diffusing into the medium, and fluorescence is observed under ultraviolet light. The medium is specified in the harmonized pharmacopoeias for the detection of Pseudomonas aeruginosa in non-sterile products.²
How selective media fit into the testing workflow
Pathogen testing normally runs in three stages: a pre-enrichment medium such as Buffered Peptone Water repairs injured cells and raises numbers, a selective enrichment then suppresses competing flora, and finally a selective differential agar isolates the target colonies. Selective agents are typically bile salts, dyes, or antibiotics; differential agents make target colonies develop a characteristic colour or morphology. Choose the combination specified by the method you follow.
Directions
Suspend 46.7 g of powder in 1 L of purified water containing 10 mL of glycerol. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
Cultural response
| Test organism | ATCC | Growth |
|---|---|---|
| Pseudomonas aeruginosa | 9027 | good-luxuriant |
| Pseudomonas aeruginosa | 27853 | good-luxuriant |
| Escherichia coli | 8739 | inhibited |
| Staphylococcus aureus | 6538 | inhibited |
Product highlights
- Food-grade raw materials, produced in an ISO 22000 certified facility
- Manufactured to the standard formulation, 46.7 g per litre
- Performance verified against standard control strains before release (Pseudomonas aeruginosa, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus)
- Available in 500 g / 5 kg / 25 kg, from laboratory to industrial scale
- COA, specification sheet, and technical data sheet available; samples on request
- Manufactured in Taiwan with reliable supply
Food grade versus laboratory grade
Most culture media suppliers use laboratory-grade raw materials, which are held to lower standards for heavy metal residues, microbial contamination control, and traceability. That is adequate for pure research but not for applications with stricter raw-material requirements. STBIO manufactures with food-grade raw materials throughout, in a facility certified to ISO 22000 food safety management.
- Food microbiology laboratories working to ISO 17025 or equivalent requirements
- Biotech manufacturers exporting fermentation products and needing full raw-material traceability
- Organisations with ESG or compliance audit requirements across their supply chain
- Companies sourcing both Halal and non-Halal products who need one consistent material grade
Frequently asked questions
01Can selective media be autoclaved?
Not always. Some media containing dyes or selective inhibitors lose their selectivity if overheated and should only be heated until fully dissolved, without autoclaving. Follow the preparation instructions for this product, and contact us if you are unsure.
02How much powder per litre?
Use 46.7 g per litre of deionised water; preparation and sterilisation conditions are given on the specification sheet.
03Which organisms is it suitable for?
Gram-negative, Pathogens, Pseudomonas, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus. See the cultural response table and the specification sheet.
04What are the equivalent brand products and standard methods?
Cross-reference: BD Difco Pseudosel Agar, Oxoid Pseudomonas Cetrimide Agar, Merck Cetrimide Agar. Standard methods: USP <62>, EP 2.6.13. Formulations may differ slightly between makers; refer to the specification sheet.
05Can it be used for food-grade applications?
Yes. It is made from food-grade raw materials in an ISO 22000 certified facility and is suitable for culturing starters for fermented products that are consumed directly.
06How is this product prepared?
Suspend 46.7 g of powder in 1 L of purified water containing 10 mL of glycerol. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
07How do I request a bulk quotation, and can you provide a COA?
Yes. This product is available in 500 g, 5 kg, 25 kg. Tell us your application and volume when requesting a quotation; we reply within one working day and can supply the COA, specification sheet, and technical data sheet.
Used in these applications
References
- 1. Brown V. I. and Lowbury E. J. L., 1965. Use of an improved cetrimide agar medium and other culture methods for Pseudomonas aeruginosa. J. Clin. Pathol., 18:752-756.
- 2. United States Pharmacopeia, current edition. Chapter <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms, USP-NF, Rockville, MD.