Cetrimide Agar

Cetrimide Agar is used in the isolation and identification of Pseudomonas aeruginosa in a laboratory setting. Cetrimide Agar is not intended for use in the diagnosis of disease or other conditions in humans.

Pseudomonas aeruginosa produces a number of water-soluble pigments, including the yellow-green or yellow-brown fluorescent pigment pyoverdin (fluorescein). When pyoverdin combines with the blue water-soluble pigment pyocyanin, the bright green color characteristic of Pseudomonas aeruginosa is created. Agar containing Cetrimide have been used successfully to isolate Pseudomonas aeruginosa from contaminated specimens.

King, Ward, and Raney developed Medium A (Tech Agar) to enhance the production of pyocyanin in Pseudomonas spp. Cetrimide Agar is prepared according to this formula with the addition of Cetrimide. Cetrimide Agar is recommended in the examination of food and in United States Pharmacopeia (USP XXIII) for use in Microbial Limit Test.


Formula Liter
Enzymatic Digest of Gelatin 20 g
Magnesium Chloride 1.4 g
Potassium Chloride 10 g
Cetrimide (Cetyltrimethylammonium Bromide) 0.3 g
Agar 13.6 g

Final pH: 7.2 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.

Supplement / Liter

Glycerol, 10 mL


  1. Suspend 45.3 g of the medium and 10 mL of glycerol in one liter of purified water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Autoclave at 121°C for 15 minutes.

Order Details

Product # Product Description
7222A Cetrimide Agar, 500 g
7222T Cetrimide Agar, 5 kg