Chromogenic selective medium for the isolation and differentiation of Candida

DESCRIPTION
ChromaticTM Candida is a chromogenic selective medium used for the isolation and differentiation of Candida species directly from clinical and nonclinical specimens permitting to distinguish among C.albicans, C.tropicalis, C.krusei, C.glabrata, C.dubliniensis and C.parapsilosis. Although Candida albicans remains the most common cause of human Candidiasis, the frequency of infection attributed to other members of the genus is also increasing. Effective treatment requires both early diagnosis and prompt initiation of therapy against fungal infection.

METHOD PRINCIPLE
Peptone provides amino acids, nitrogen, carbon, vitamins and minerals for organisms growth. Chloramphenicol is the selective agent inhibiting most of the bacteria. Chromogenic mix allows to identify the Candida genus on the basis of the color and morphology of the colonies. Agar is the solidifying agent.

TYPICAL FORMULA (g/l)

PREPARATION
Dehydrated medium : Suspend 50.7 g of the powder in 1 liter of distilled or deionized water. Mix well. Heat to boil shaking frequently until completely dissolved. DO NOT AUTOCLAVE.
Medium in bottles : Melt the content of the bottle in a water bath at 100°C (loosing the cap partially removed) until completely dissolved. Then screw the cap and check the homogeneity of the dissolved medium, if it is the case turning the bottle upside down. Cool at 45-50°C, mix well avoiding foam formation and aseptically distribute into Petri dishes.

TEST PROCEDURE
Inoculate the medium by direct streaking, spread plating or membrane filtration method. Incubate aerobically at 30-37°C for 24-48 hours.

INTERPRETING RESULTS
After incubation observe the color and the morphology of the colonies and interpret the results as indicated in the ID table.

ID TABLE

APPEARANCE
Dehydrated medium: free-flowing, homogeneous, light beige.
Prepared medium: slightly opalescent, very light beige.

STORAGE
The powder is very hygroscopic, store the powder at 10-30°C, in a dry environment, in its original container tightly closed. Store bottles and prepared plates at 2-8°C away from light. Do not use the product beyond its expiry date on the label or if product shows any evidence of contamination or any sign of deterioration.

SHELF LIFE
Dehydrated medium: 4 years.
Medium in bottles: 1 year.
Ready-to-use plates: 6 months.

QUALITY CONTROL
Plates are inoculated with the microbial strains indicated in the QC table.
Inoculum for productivity: 50-100 CFU
Inoculum for selectivity: 10⁴-10⁶ CFU.
Incubation conditions: aerobically at 35 ± 2°C for 24-48 hours.

WARNING AND PRECAUTIONS
The product does not contain hazardous substances in concentrations exceeding the limits set by current legislation and therefore is not classified as dangerous. It is nevertheless recommended to consult the safety data sheet for its correct use. The product is intended for in vitro diagnostic use and must be used only by properly trained operators.

DISPOSAL OF WASTE
Disposal of waste must be carried out according to national and local regulations in force.

BIBLIOGRAPHY

1. Odds, F.C. And Bernaerts. 1994. CHROMagar Candida, a new differential medium for presumptive identification of clinically important Candida species. J. Clin. Microbiol. 32: 1923-1929.
2. Wingard, JR. Importance of Candida species other than C. albicans as pathogens in oncology patients. Clin Infect Dis. 1995; 20: 115–25.
3. Pfaller, Huston and Coffman. 1996. J. Clin. Microbiol. 32: 1923-1929.
4. Maertens JA. History of the development of azole derivatives. J Clin Microbiol Infect. 2004; 10: 1–10.

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