Cetrimide Agar
Composition-
Gelatin Pepton 20.0 - gm/per ltr.
Magnesium chloride – 1.4 gm/ ltr.
Potassium sluphide - 10.0 gm/ ltr
Cetrimide
– 0.30 gm/ ltr.
Agar
– 15.0 gm / ltr.
PH
– 7.2
 Cetrimide Agar is a selective agar used for the isolation of Psuedomonas
aeruginosa.
 Cetrimide is quaternary ammonium salt which is the selective agent in the
medium. It inhibits a wide varierty of microorganism including pseudomonas
species other than pseudomonas aeruginosa . It acts as a cationic detergent
denaturing the bacterial cell membrane.
 Cetrimide also serves as a way to detect the ability of organisms that can
produce fluorescent pigmets .Psuedomonas aeruginosa produces soluble iron
pigments like pyocyanin and pyoverdin. P.aeruginoa is identified by the
observation of bright green pigment under UV light .when pyoverdine combines
with pyocyanin in the medium production of bright green colour pigment is
seen.
 Cetrimide ,potassium sulfate ,magnesium chloride enables and also stimulates
the production of both pyocyanin and pyoverdin in the medium
 Pancreatic digest provides nitrogen ,carbon source necessary for the growth of
P. aeruginosa
 Gycerol is the carbon source
 Agar acts as solidifying agent
P.aeruginosa showing green pigment
P.aeruginosa showing fluorescence under
UV light.