Cetrimide agar is a type of agar

Agar

Agar or agar-agar is a gelatinous substance derived from a polysaccharide that accumulates in the cell walls of agarophyte red algae. Throughout history into modern times, agar has been chiefly used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture medium...

 used for the selective isolation of the gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 bacteria, Pseudomonas aeruginosa

Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...

. As the name suggests, it contains cetrimide, which is the selective agent against alternate microbial flora. Cetrimide also enhances the production of Pseudomonas pigments such as pyocyanin and fluorescein

Fluorescein

Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....

, which show a characteristic blue-green and yellow-green colour, respectively.

Cetrimide agar is widely used in
the examination of cosmetics, pharmaceuticals and clinical
specimens to test for the presence of Pseudomonas aeruginosa.

External links

• Cetrimide Agar Description & Formulation