Cat. no. C7780 CRITERION™ Caffeic Acid Agar 68gm
Cat. no. C7781 CRITERION™ Caffeic Acid Agar 500gm
Cat. no. C7782 CRITERION™ Caffeic Acid Agar 2kg
Cat. no. C7783 CRITERION™ Caffeic Acid Agar 10kg
Cat. no. C7784 CRITERION™ Caffeic Acid Agar 50kg


Hardy Diagnostics CRITERION™ Caffeic Acid Agar is recommended for the selective isolation and differentiation of Cryptococcus neoformans.

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.


Cryptococcus neoformans is an encapsulated yeast that produces the enzyme phenoloxidase, an enzyme necessary in melanin synthesis. When in the presence of caffeic acid, the enzyme attacks the acid resulting in the production of melanin. Subsequently, melanin is absorbed by the cell wall of the yeast producing tan to brown pigmented colonies.

The brown pigmented colonies of Cryptococcus neoformans were observed by Staib in 1962 when he grew cultures of the yeast on media containing Guizotia abyssinica seeds.(6) It was later determined that the seeds contain caffeic acid, which served as the melanin-producing substrate.

In 1966, Shields and Ajello modified Staibs Birdseed Agar by making the medium selective with an antimicrobic additive.(7) CRITERION™ Caffeic Acid Agar is a modification of the latter formula.


Gram weight per liter: 34.0gm/L
Ammonium Sulfate 5.0gm
Glucose 5.0gm
Yeast Extract 2.0gm
Dipotassium Phosphate 0.8gm
Magnesium Sulfate 0.7gm
Caffeic Acid 0.18gm
Chloramphenicol 0.05gm
Ferric Citrate 0.05gm
Agar 20.0gm

Final pH 6.5 +/- 0.2 at 25ºC.

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


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 culture medium at 2-8ºC.



1. Suspend 34.0gm 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.

4. Cool to 45-50ºC.


Specimen Collection: Infectious material should be submitted directly to the laboratory without delay and protected from excessive heat and cold. Consult listed references for information on specimen collection.(2-5)


For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. G213.


Yeasts other than C. neoformans may rarely produce brown pigmentation on media containing caffeic acid.

A Sabouraud Dextrose Agar (Cat. no. W70) control should be inoculated in parallel to the Caffeic Acid Agar slant to ensure that a dark pigment is not naturally produced by the colonies. Aureobasidium, Sporothrix, Wangiella, and Phialophora may produce dark brown colonies, but the pigment will not be a result of enzymatic activity which is made evident by pigmentation developing in colonies on all media.

Rare strains of C. neoformans may not produce pigmented colonies.

Specimens heavily contaminated with bacteria may obscure growth and/or pigmentation of C. neoformans.


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


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Cryptococcus neoformans
ATCC ® 32045
A 72-96hr 15-30°C Aerobic Growth; brown to black pigmented colonies
Escherichia coli
ATCC ® 25922
B 24hr 35°C Aerobic Inhibited

User Quality Control


CRITERION™ Caffeic Acid Agar powder should appear homogeneous, free-flowing, and light beige in color. The prepared media should appear slightly opaque, with precipitate, and light gray in color.


1. 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.

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

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

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

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

6. Staib, F. 1962. Hyg. Infektionskr. Med. Mikeobiol. Immunol. Virol.; 148:466-475.

7. Shields, A.B. and Ajello, L. 1966. Medium for Selective Isolation of Cryptococcus neoformans, Service; 151:208-209.

8. Denning, D.W., et al. 1990. Journal of Clinical Microbiology; Vol. 28, No. 11, p. 2565-2567.

9. La Rocco, Mark, Ph.D. 1992. Clinical Microbiology Newsletter; Vol. 14, No. 23, p. 177-181.

ATCC is a registered trademark of the American Type Culture Collection.