Composition

* Dehydrated powder, hygroscopic in nature, store, in a dry place in tightly- sealed containers below 25°C and protect from direct Sunlight.

Instructions for Use

Dissolve 42.72gms in 1000ml of distilled water. Gently heat to boiling with gentle swirling and dissolve the medium completely. DO NOT AUTOCLAVE. DO NOT OVER HEAT. Cool to 50ºC. Mix well and pour  into sterile Petri – plates.

Appearance: Light amber colour, clear

pH (at 250C): 6.3 ± 0.2

Principle

CHROMOGENIC CANDIDA AGAR or Chromogenic Candida Differential Agar is used for selective isolation & differentiation of Candida species from mixed flora.  Chromogenic  Candida  Agar  allows  the easy and rapid identification and differentiation of all 3 species by producing easy-to-read results in one plate, since they present different colored colonies. This medium was optimized for sensitivity  to  C.  albicans, C. tropicalis, and Candida kefyr and was tested with a wide range of  yeasts  and  some  molds. Peptone special, yeast extract, provide nitrogenous, carbonaceous compounds and other essential growth nutrients. Chloramphenicol suppresses bacterial flora. The different species of Candida produce different kinds of infections. Candida albicans is the most common and is usually  susceptible  to  the  antifungal  agents’ azole group. However, Candida glabrata, Candida tropicalis  and  Candida  krusei  are  azole-tolerant, thus the rapid identification of the different species of Candida is essential for its correct diagnosis and treatment. In this chromogenic medium, the three  different species of  Candida albicans, Candida  tropicalis  and Candida krusei can be differentiated due to the chromogenic substrates present within the medium. Colonies of Candida albicans are green, those of Candida krusei are  purple-pink  and  those  of  Candida tropicalis are blue. C. albicans test strains gave turquoise blue colonies, as claimed, although C. dubliniensis strains gave a similar colony color. Chromogenic Candida Agar is reported to give green colonies of C. albicans and metallic blue colonies of C. tropicalis. In this study, most C. albicans strains gave green colonies after 48 h of incubation. Colonies of the three C. dubliniensis strains were green. Only 7 of 10 C. tropicalis strains gave the predicted steel blue colony color. Chromogenic Candida Agar is also reported to detect C. krusei colonies by their fuzzy rose color. Three of the four test strains gave pink colonies after 48 h of incubation, but after only 24 h of incubation the colony colors of two of these strains varied from pink to purple. The remaining C. krusei strain gave purple or white colonies even after 48 h of incubation. In

addition, the usefulness of colony color in identification of C. krusei appears to be limited as several other yeasts gave pink colonies on Chromogenic Candida Agar, including C. lusitaniae, C. parapsilosis, and B. capitatus.

Interpretation

Cultural characteristics observed after inoculating (102 – 103CFU/ml), on incubation at 30ºC  for 24  – 48  and  48 – 72 hour.

References

1. Aamlid, K. H., G. Lee, R. G. Price, A. C. Richardson, B. V. Smith, and S. A. Taylor. (1989). Development  of improved chromogenic substrates for the detection and assay of hydrolytic enzymes. Chem. Ind. (London):106– 108. (1989).
2. Al-Doory, Y. Laboratory medical mycology. Henry Kimpton Publishers, London,  United  Kingdom.Perry J.L. and Miller G.R., J. Clini. Microbiol., 25:2424-2425. (1980).
3. Odds, F.C. Candida and candidiosis, 2nd ed, Baillière Tindall, London, England. (1988).
4. Rousselle P., Freydiere A., Couillerot P., de Montclos H. and Gille Y., J. Clin. Microbiol., 32:3034-3036. (1994).