Cetrimide agar is primarily used for the selective isolation of which organism?

Cetrimide agar is a selective medium that is specifically designed for the isolation of Pseudomonas aeruginosa, which is an important opportunistic pathogen often associated with infections in immunocompromised individuals, burn victims, and patients with cystic fibrosis. The agar contains cetrimide, a quaternary ammonium compound, which inhibits the growth of many other bacteria while allowing Pseudomonas aeruginosa to thrive.

Pseudomonas aeruginosa can utilize the nutrients present in the medium and often produces characteristic pigments such as pyocyanin, which gives the culture a distinctive blue-green color. This not only aids in the identification of the organism but also confirms its presence in clinical specimens.

While other organisms may also grow on cetrimide agar, the formulation of the medium specifically promotes the growth of Pseudomonas aeruginosa and is thus most valuable in isolating this particular species in laboratory settings.