CRITERION™ POTATO DEXTROSE AGAR (PDA)

Cat. no. C6620 CRITERION™ Potato Dextrose Agar 72gm
Cat. no. C6621 CRITERION™ Potato Dextrose Agar 500gm
Cat. no. C6622 CRITERION™ Potato Dextrose Agar 2kg
Cat. no. C6623 CRITERION™ Potato Dextrose Agar 10kg
Cat. no. C6624 CRITERION™ Potato Dextrose Agar 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ Potato Dextrose Agar is used for the cultivation and identification of fungi.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY

Potato Dextrose Agar contains dextrose as a carbohydrate source, and potato infusion to supply other necessary growth requirements. Potato infusion provides a nutrient base for luxuriant growth of most fungi. Dextrose serves as a growth stimulant. The incorporation of tartaric acid (TA) in the medium lowers the pH to 3.5 thereby inhibiting bacterial growth.

Potato Dextrose Agar is formulated according to procedures in Standard Methods for the Examination of Dairy Products and Compendium of Methods for the Microbiological Examination of Foods.(1,2)

The American Public Health Association and the Association of Analytical Chemists recommend Potato Dextrose Agar for use in plate counts of yeasts and molds in the examination of dairy products and foods.(15,16,18,20) This product is recommended by the U.S. Pharmacopeia for Microbial Limit Tests.(17) Potato Dextrose Agar is used in slide preparations of fungi for the stimulation of sporulation and in the maintenance of dermatophyte stock cultures. Additionally, the medium is useful for differentiation of atypical dermatophytes based on pigment production.(19)

FORMULA

Gram weight per liter: 36.0gm/L
Dextrose 20.0gm
Potato Infusion 4.0gm
Agar 12.0gm

Final pH 5.6 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light beige.

Store the prepared media, except plated, at 2-30ºC. Prepared plated media should be stored at 2-8ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 36.0gm of the dehydrated culture media in 1 liter of distilled or deionized water.

2. Heat to boiling and mix to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

PROCEDURE AND INTERPRETATION OF RESULTS

For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. W60.

LIMITATIONS

Potato Dextrose Agar (without TA) is not for use as a primary isolation medium. Direct inoculation of specimens will result in erroneous results.

For proper identification of mold fungi, microscopic examination and evaluation of morphological structures is required.

Further biochemical, physiological, serological tests and microscopic morphology of pure cultures are recommended for complete identification. For more information see appropriate references.(8-13)

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Trichophyton mentagrophytes
ATCC ® 9533
G 7 days 15-30°C Aerobic Growth; may take up to 7 days
Trichophyton rubrum
ATCC ® 28188
G 3-4 weeks 15-30°C Aerobic Growth visible in 7 days, may take 3-4 weeks for color to develop on reverse side of colony
Aspergillus brasiliensis
formerly A. niger **
ATCC ® 16404

J 1-5 days 15-30°C Aerobic Growth; may take up to 5 days
Candida albicans **
ATCC ® 10231
J 1-3 days 15-30°C Aerobic Growth

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ Potato Dextrose Agar powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear slightly opalescent, and light amber in color.

REFERENCES

1. Marshall, R.T., ed. 1992. Standard Methods for the Examination of Dairy Products, 16th ed. APHA, Washington, D.C.

2. Vanderzant, C. and D.F. Splittstoesser, (ed.). 1992. Compendium of Methods for the Microbiological Examination of Foods, 3rd ed. APHA, Washington, D.C.

3. Standard Methods for the Examination of Water and Waste Water, 19th ed. 1995. APHA, Washington, D.C.

4. Association of Official Agricultural Chemists, 10th ed. 1965. p. 737.

5. U.S. Pharmacopeia, 22nd rev. 1990. U.S. Pharmacopeial Convention, Rockville, MD.

6. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

7. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.

8. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

9. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

10. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

11. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

12. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

13. St. Germain, Guy, et al. 1996. Identifying Filamentous Fungi. Star Publishing Company, Belmont, CA.

14. Campbell, M.C. and J.L. Stewart. 1980. The Medical Mycology Handbook, John Wiley and Sons, New York, NY.

15. Richardson, (ed.). 1985. Standard Methods for the Examination of Dairy Products, 15th ed. American Public Health Association, Washington, D.C.

16. Speck, (ed.). 1984. Compendium of Methods for the Microbiological Examination of Foods, 2nd ed. American Public Health Association, Washington, D.C.

17. Association of Official Analytical Chemists (AOAC), 15th ed. 1990. Arlington, VA.

18. Robell and Taplin. 1970. Dermatophytes, University of Miami Press.

19. U.S. Food and Drug Administration. Bacteriological Analytical Manual. AOAC, Arlington, VA.
http://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm.

20. The Official Compendia of Standards. USP General Chapter <61> Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests. USP-NF. United States Pharmacopeial Convention Inc., Rockville, MD.

21. The Official Compendia of Standards. USP General Chapter <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms. USP-NF. United States Pharmacopeial Convention Inc., Rockville, MD.


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