Cetrimide (Pseudosel) Agar Base
CAT: AS‑1171 
Selective Medium for Pseudomonas aeruginosa
 
Overview
Cetrimide Agar Base (CAT: AS‑1171) is a selective culture medium specifically formulated for the isolation and presumptive identification of Pseudomonas aeruginosa. The medium contains cetrimide, a quaternary ammonium compound that disrupts bacterial membranes, inhibiting most non‑Pseudomonas organisms and enhancing selectivity. Gelatin peptone and sodium chloride provide essential nutrients and maintain osmotic balance, while magnesium chloride and potassium sulfate stimulate the production of pyocyanin, the characteristic blue‑green pigment of P. aeruginosa, aiding in visual identification.
 
Applications
Clinical microbiology: isolation of P. aeruginosa from wound, respiratory, and urine samples.
Environmental monitoring: detection in water and surface testing in healthcare and industrial facilities.
Industrial microbiology: quality control in pharmaceuticals, cosmetics, and manufacturing.
Visual screening: identification via colony color and morphology.
 
Key Features
Highly selective: cetrimide inhibits competing flora, ensuring recovery of P. aeruginosa.
Pigment enhancement: promotes pyocyanin production for easy visual identification.
Nutrient‑rich composition: supports robust growth of target organisms.
Versatile use: applicable in clinical, pharmaceutical, environmental, and industrial microbiology.
 
Composition (per liter)
Pancreatic Digest of Gelatin (Gelatin Peptone): 20.0 g Potassium Sulfate (K₂SO₄): 10.0 g
Magnesium Chloride (MgCl₂·6H₂O): 1.4 g
Cetrimide (Cetyltrimethylammonium Bromide): 0.3 g
Glycerol (added separately): 10.0 mL
Agar: 13.6–15.0 g
Final pH: 7.2 ± 0.2 at 25 °C
 
Notes on Composition 
Cetrimide is the selective agent (quaternary ammonium compound) that inhibits most bacteria except Pseudomonas aeruginosa. Gelatin peptone provides nitrogen and growth factors. Potassium sulfate and magnesium chloride stimulate pyocyanin pigment production, aiding visual identification. Glycerol serves as an additional carbon source, enhancing pigment expression. Agar solidifies the medium.
 
Preparation
Suspend 46.7 g of dehydrated base in 990 mL distilled water. Add 10 mL glycerol. Heat to dissolve completely. Sterilize by autoclaving at 121 °C for 15 minutes. Cool to 45–50 °C and pour plates (~20 mL per 90 mm plate).
 
Summary
The complete formula includes gelatin peptone, potassium sulfate, magnesium chloride, cetrimide, glycerol, and agar. Your earlier version was missing glycerol and the exact weights for potassium sulfate and magnesium chloride. This corrected composition is the internationally recognized standard for Cetrimide Agar Base, ensuring selective isolation and pigment enhancement of Pseudomonas aeruginosa
 
Storage
Dehydrated medium: Store sealed and dry at 15–30 °C.
Prepared plates: Store at 2–8 °C, away from light. Discard if contamination or color change occurs.
 
Safety & Compliance
For Research Use Only — Not for Human or Animal Consumption.
SDS, COA, and TDS available for download.
Conforms to international standards for selective isolation of Pseudomonas aeruginosa.
 
FAQ
Q1: What organism is Cetrimide Agar Base selective for? A1: Pseudomonas aeruginosa.
Q2: How does the medium aid identification? A2: By promoting pyocyanin pigment production, resulting in blue‑green colonies.
Q3: Can this medium be used for environmental monitoring? A3: Yes, it is widely used for water and surface testing in healthcare and industry.