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Use of CHROMagar Candida

CHROMagar Candida or HiCrome candida differential agar recommendation is for rapid isolation and identification of Candida species from mixed cultures in clinical and non-clinical samples.

Composition of CHROMagar Candida

Ingredients       Gm / Litre

Peptone, special:  15.000

Yeast extract: 4.000

Dipotassium hydrogen phosphate: 1.000

Chromogenic mixture: 7.220

Chloramphenicol:0.500

Agar: 15.000

Final pH (at 25°C) 6.3±0.2

Preparation of CHROMagar Candida medium

1. Suspend 42.72 grams in 1000 ml distilled water.
2. Heat to boiling to dissolve the medium completely.
3. DO NOT AUTOCLAVE.
4. Cool to 45-50°C.
5. Mix well and pour into sterile Petri plates.

Principle And Interpretation of CHROMagar Candida

Perry and Miller reported that Candida albicans produces an enzyme b -N-acetyl- galactosaminidase and according to Rousselle et al incorporation of chromogenic or fluorogenic hexosaminidase substrates into the growth medium helps in identification of C. albicans isolates directly on primary isolation. HiCrome Candida Differential Agar is a selective and differential medium, which facilitates rapid isolation of yeasts from mixed cultures and allows differentiation of Candida species namely C. albicans, C. krusei, C. tropicalis and C. glabrata on the basis of coloration and colony morphology. On this medium results are obtained within 48 hours and it is useful for the rapid and presumptive identification of common yeasts in Mycology and Clinical Microbiology Laboratory. Peptone special and yeast extract provides nitrogenous, carbonaceous compounds and other essential growth nutrients. Phosphate buffers the medium well. Chloramphenicol suppresses the accompanying bacterial flora. C. albicans appear as light green colored smooth colonies, C. tropicalis appear as blue to metallic blue colored raised colonies. C. glabrata colonies appear as cream to white smooth colonies, while C. krusei appear as purple fuzzy colonies.

Type of specimen

Clinical samples – skin scrapings, urine or stored Candida species or yeast colonies

Procedure

1. Stored Candida species were inoculated in HiCrome candida differential agar.
2. It was then incubated at 25-30°C for 48 hours.

Observation of CHROMagar Candida

After two days of incubation above shown type of figure observed.

1. Green
2. Green
3. purple, fuzzy
4. blue to purple

Result of CHROMagar Candida

1. Candida albicans
2. Candida albicans
3. Candida krusei
4. Candida tropicalis

Note: as shown above figure

Cultural characteristics of CHROMagar Candida

After an incubation at 25-30°C for 40-48 hours.

Organism                                               Growth                       Color of Colony

Candida albicans ATCC 10231      good-luxuriant          green

Candida glabrata ATCC 15126    good-luxuriant           cream to white

Candida krusei ATCC 24408        good-luxuriant          purple, fuzzy

Candida tropicalis ATCC 750       good-luxuriant           blue to purple

Escherichia coli ATCC 25922        inhibited

Staphylococcus aureus ATCC 25923  inhibited

Limitations of using CHROMagar Candida

1. Variations in color intensity may be observed for Candida isolates depending on the presence of enzymes.
2. Other Candida species may produce light mauve colored colonies which is also produced by other yeast cells. This must be confirmed by further biochemical tests.
3. Other filamentous fungi also exhibit color on this medium.

Further Reading

1. A Text Book of Medical Mycology. Editor: Jagdish Chandar.  Publication Mehata, India.
2.  Practical Laboratory Mycology. Editors: Koneman E.W. and G.D. Roberts, 3rd ed 1985, Publisher Williams and Wilkins, Baltimore.
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3071170/
4. https://www.bd.com/resource.Aspx?IDX=9019
5. https://himedialabs.com/TD/M1297A.pdf
6. https://academic.oup.com/mmy/article/48/1/29/1247981