CETRIMIDE AGAR PLATE is used for the selective isolation of Pseudomonas aeruginosa from samples. The medium contains quaternary ammonium, cationic detergent compound like Cetrimide which has a property to inhibit all the bacteria except P. aeruginosa thus making the medium selective for Pseudomonas aeruginosa. Cetrimide causes release of nitrogen and phosphorus from bacterial cells other than P. aeruginosa. The media are gamma irradiated in the packaging material to assure a reduction of the microbial load potentially present in the medium, on the dishes, and on the packaging materials.