Cetrimide Agar Base (w/1.3% Agar) is recommended for the selective isolation of Pseudomonas aeruginosa from various materials. It can also be used for determining the ability of an organism to produce fluorescein and pyocyanain. Cetrimide (N-acetyl-N-N,N-trimethylammaonium bromide) in the medium acts as a selective agent inhibiting bacteria other than Pseudomonas aeruginosa.