Cetrimide agar base_td

CETRIMIDE AGAR is used for the selective isolation of Pseudomonas aeruginosa from clinical samples. The medium is a modification of the medium proposed by Brown and Lowbury (1965) for the isolation and differentiation of Pseudomonas aeruginosa from various materials.

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www.tmmedia.in PRODUCT DATA SHEET

INTENDED USE
Cetrimide Agar Base For selective isolation of Pseudomonas aeruginosa from clinical samples.

COMPOSITION

Ingredients Gms/Ltr
Pancreatic digest of gelatin 20.000
Agar 15.000
Potassium sulphate 10.000
Magnesium chloride 1.400
Cetrimide 0.300

PRODUCT SUMMARY AND EXPLAINATION
CETRIMIDE AGAR is used for the selective isolation of Pseudomonas aeruginosa from clinical samples.
The medium is a modification of the medium proposed by Brown and Lowbury (1965) for the
isolation and differentiation of Pseudomonas aeruginosa from various materials. 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.
Cetrimide Agar is recommended in the United States Pharmacopoeia XXVI and European
Pharmacopoeia IV for use in Microbial Limit Tests. The formulation is also in the A.O.A.C.
guidelines for isolation of Pseudomonas aeruginosa from cosmetics and in the A.O.A.C. method for
testing disinfectants on hard surfaces.

PRINCIPLE
Pancreatic digest of gelatin is a source of carbon and nitrogen for the growth of microorganisms.
Agar is a solidifying agent. Sodium chloride maintains osmotic equilibrium in the medium.
Magnesium chloride and Potassium sulphate stimulates the bacterium to produce and secrete a
pigment called pyocyanin due to which the colony colour turns light green, and also they forms a
grape like odour. Cetrimide is a quaternary ammonium salt, which acts as a cationic detergent that
reduces surface tension in the point of contact and has precipitant, complexing and denaturing effects
on bacterial membrane proteins. It exhibits inhibitory actions on a wide variety of microorganisms
including Pseudomonas species other than Pseudomonas aeruginosa.
Goto and Enomoto (1970) recommend the addition of 15 µg nalidixic acid/ml to improve the
inhibition of the accompanying microbial flora.

INSTRUCTIONS FOR USE
CETRIMIDE AGAR BASE TM 060

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www.tmmedia.in PRODUCT DATA SHEET
1. Dissolve 46.7 grams in 1000 ml distilled water containing 10 ml glycerol.
2. Gently heat to boiling with gentle swirling and dissolve the medium completely.
3. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
4. Cool to 45-50°C.
5. If desired, rehydrated contents of 1 vial of Nalidixic Selective Supplement (TS 020) may be
added aseptically to 1000 ml medium.
6. Mix well and pour into sterile Petri plates.

CONTROL SPECIFICATIONS
Appearance Dehydrated powder: Cream to yellow colour, homogenous free flowing powder
Appearance of the prepared medium: Light amber colour, opalescent gel with slight precipitate.
pH (at 25°C) : 7.2 ± 0.2

INTERPRETATION
Cultural characteristics observed after incubation at 35 ± 2°C for 24 hours.

Organism ATCC
Inoculum
(CFU/ml)
Growth
Pseudomonas aeruginosa 27853 50-100 Luxuriant
Pseudomonas aeruginosa 9027 50-100 Luxuriant
Escherichia coli 25922 ≥ 1000 Inhibited
Staphylococcus aureus 25923 ≥ 1000 Inhibited

STORAGE & STABILITY
Dehydrated powder, hygroscopic in nature, store in a dry place, in tightly-sealed containers below
25°C and protect from direct Sunlight. Under optimal conditions, the medium has a shelf life of 4
years. When the container is opened for the first time, note the time and date on the label space
provided on the container. After the desired amount of medium has been taken out replace the cap
tightly to protect from hydration.



REFERENCES
1. Forbes B. A., Sahm A. S. and Weissfeld D. F., Bailey & Scotts Diagnostic Microbiology, 10th
Ed., 1998, Mosby, Inc., St. Louis, Mo.

3. Page 3 Manufacturer Address: A- 902A, RIICO Industrial Area, Phase III, Bhiwadi-301019.


www.tmmedia.in PRODUCT DATA SHEET
2. Williams, (Ed.), 2005, Official Methods of Analysis of the Association of Official Analytical
Chemists, 19th Ed., AOAC, Washington, D.C.
3. Goto, S., a. Enomoto, S.: Nalidixic acid cetrimide agar. A new selective plating medium for the
selective isolation of Pseudomonas aeruginosa. - Japan J. Microbiol., 14; 65-72 (1970).
4. Brown, V.I. and Lowbury E.J.L. (1965): Use of improved cetrimide agar medium and other
culture methods for Pseudomonas aeruginosa. J. Clin. Pathol. 18: 752-756.
5. United States Pharmacopeia 2002. Microbiological Limit Tests, United States Pharmacopeia, 26th
Ed. United States Pharmacopial Convention, Rockville, M.D.
6. European Pharmacopeia 2002. Microbial Examination of Non-Sterile Products, (Test for
Specified Microorganisms). European Pharmacopoeia, 4th Ed.
7. Official Analytical Chemists. 1995. Bacteriological Analytical Manual, 8th Ed. AOAC International,
Gaithersburg, M.D.

NOTE: Please consult the Material Safety Data Sheet for information regarding hazards and safe
handling practices.