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Cetrimide Agar

Name: Cetrimide Agar
SKU: CA-G
Availability: InStock

Cetrimide Agar

$22.00 – $190.00

100 g, 500g, 2 kg
Number of sizes: 3
Type: Powder

Dehydrated Powder

No sub-products available for this product.

SKU: CA-G Category: Dehydrated Powder

Description

Intended Use and Principle of Procedure

This medium conforms with specifications of The United States Pharmacopeia (USP). Cetrimide Agar (Pseudosel) Agar is used for the selective isolation and identification of Pseudomonas aeruginosa.

The production of pyocyanin is stimulated by the magnesium chloride and potassium sulfate in the medium. Cetrimide Agar is a quaternary ammonium compound which is inhibitory to a wide variety of bacterial species including Pseudomonas species other than P. aeruginosa.

Summary and Explanation

King et al. developed Medium A (Tech Agar) for the enhancement of pyocyanin production by Pseudomonas. 1 Cetrimide (Pseudosel) Agar has the formula for Tech Agar but is modified by the addition of cetrimide for the selective inhibition of organisms other than that P. aeruginosa. 2 In 1951, Lowbury described the use of 0.1% cetrimide in a selective medium for P. aeruginosa. 2 Because of the increased purity of the inhibitory agent, the concentration was later reduced, as reported by Lowbury and Collins in 1955.3 Brown and Lowbury employed incubation at 37°C with examination after 18 and 42 hours of incubation.4 Strains of P. aeruginosa are identified from specimens by their production of pyocyanin, a blue, water-soluble, nonfluorescent, phenazine pigment in addition to their colonial morphology5 and the characteristic grapelike odor of aminoacetophenone.6 P. aeruginosa is the only species of Pseudomonas or gramnegative rod known to excrete pyocyanin. Cetrimide (Pseudosel) Agar, therefore, is a valuable culture medium in the identification of this organism. Cetrimide Agar (Pseudosel) Agar is widely recommended for use in the examination of cosmetics,7 pharmaceuticals8 and clinical specimens5,9 for the presence of P. aeruginosa, as well as for evaluating the efficacy of disinfectants against this organism.

Formulae

Pancreatic Digest of Gelatin	20.0g
Magnesium Chloride	1.4g
Potassium Sulfate	10.0g
Cetrimide (Tetradecyltrimethylammonium Bromide)	0.3g
Agar	13.6g

Procedure

Use standard procedures to obtain isolated colonies from specimens. Incubate plates in an inverted position (agar side up) at 35 ± 2°C for 18-48 hours. Inoculate tubes with either pure cultures or with specimen material. Incubate tubes at 35 ± 2°C for 18-24 hours in an aerobic atmosphere.

Directions for Preparation from Dehydrated Product

1. Suspend 45.3 g of the powder in 1 L of purified water containing 10 mL of glycerol. Mix thoroughly.

2. Heat with frequent agitation and boil for 1 minute to completely dissolve the powder.

3. Autoclave at 121°C for 15 minutes.

4. Test samples of the finished product for performance using stable, typical control cultures.

Identification Specification and Cultural Response

Dehydrated Appearance:	Beige, free-flowing, homogeneous.
Prepared Appearance: Solution:	Light amber, opalescent, with precipitate. 4.53% solution with 1% glycerol, soluble in purified water upon boiling. Solution is light amber, opalescent, with a precipitate
pH:	7.2 ± 0.2
Cultural Response:	Prepare the medium per label directions. Inoculate and incubate at 35 ± 2°C for 18-48 hours.
Reaction	4.53%
Solution	25°C

Microorganism	ATCC	CFU	Recovery
Escherichia coli	25922	103-2×103	Inhibition
Pseudomonas aeruginosa	27853	102	Good
Staphylococcus aureus	25923	102-2×103	Inhibition

Limitations Of The Procedure

1. The type of peptone used in base may affect pigment production.

2. No single medium can be depended upon to exhibit all pigment-producing P. aeruginosa strains.

3. Occasionally some enterics will exhibit a slight yellowing of the medium; however, this coloration is easily distinguished from fluorescein production since this yellowing does not fluoresce.

4. Some nonfermenters and some aerobic sporeformers may exhibit a water-soluble tan to brown pigmentation on this medium. Serratia strains may exhibit a pink pigmentation.

5. Studies of Lowbury and Collins13 showed P. aeruginosa may lose its fluorescence under UV if the cultures are left at room temperature for a short time. Fluorescence reappears when plates are reincubated.

Expected Results

Colonies that are surrounded by a blue-green pigment and fluoresce under short wavelength (254 nm) ultraviolet light may be presumptively identified as Pseudomonas aeruginosa. Note, however, that certain strains of P. aeruginosa may not produce pyocyanin. Other species of Pseudomonas do not produce pyocyanin, but fluoresce under UV light. Most non-Pseudomonas species are inhibited, and some species of Pseudomonas may also be inhibited. Gram staining, biochemical tests and serological procedures should be performed to confirm findings. .

References

1. King, Ward and Raney. 1954. J. Lab Clin. Med. 44:301.

2. Lowbury. 1951. J. Clin. Pathol. 4:66.

3. Lowbury and Collins. 1955. J. Clin. Pathol. 8:47.

4. Brown and Lowbury. 1965. J. Clin. Pathol. 18:752.

5. Kiska and Gilligan. 1999. In Murray, Baron, Pfaller, Tenover and Yolken (ed.), Manual of clinical microbiology, 7th ed. American Society for Microbiology, Washington, D.C.

6. Gilardi. 1991. In Balows, Hausler, Herrmann, Isenberg and Shadomy (ed.), Manual of clinical microbiology, 5th ed. American Society for Microbiology, Washington, D.C.

7. Hitchins, Tran and McCarron. 1995. FDA bacteriological analytical manual, 8th ed. AOAC International, Gaithersburg, Md.

8. United States Pharmaceutical Convention, Inc. 2001. The United States pharmacopeia 25/The national formulary 20 – 2002. United States Pharmaceutical Convention, Inc., Rockville, Md.

9. Forbes, Sahm and Weissfeld. 1998. Bailey & Scott’s diagnostic microbiology, 10th ed. Mosby, Inc., St. Louis, Mo.

10. Horwitz (ed.). 2000. Official methods of analysis of AOAC International, 17th ed., vol. 1. AOAC International, Gaithersburg, Md.

11. MacFaddin. 1985. Media for isolation-cultivation-identification-maintenance of medical bacteria, vol. 1. Williams & Wilkins, Baltimore, Md.

12. Goto and Enomoto. 1970. Jpn. J. Microbiol. 14:65.

13. Lowbury and Collins. 1955. J. Clin. Pathol. 8:47.

Additional information

Size	100g, 500g, 2kg

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Cetrimide Agar

Cetrimide Agar

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