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BIGGY (NICKERSON) CANDIDA AGAR

 

Used for the isolation of Candida from clinical specimens.

 

Code: CB1/3802

 

Typical formula g/l

 

Yeast extract 1.0
Bi-ammonium citrate   

5.0

Sodium sulphite

3.0

Glucose 10.0
Glycine 10.0
Agar 15.0

 

Final pH 6.8  +/- 0.2  

      

Directions

Suspend 44g in 1000 ml of cold distilled water; heat with frequent agitation and boil for not more than one minute. Cool to about 50°C, swirl to disperse the insoluble matter and pour into plates. Do not overheat or autoclave.

 

Description

The medium, which has a composition unfavourable to the deve­lopment of schizomycetes, permits the isolation of Candida spp. from clinical specimens (mucous secretions, skin or nail fragments) containing mixed flora.  Candida Agar contains a bismuth indicator, which turns black in the presence of hydrogen sulphide: according to the sulphite­ reducing capacity of the species being examined, the colonies ap­pear more or less black.  C. albicans grows on the medium with metallic black colo­nies, non-pathogenic candida with brown colonies. According to Nickerson, some yeasts (among those C. albicans, C. krusei, C. tropicaiis) also develop sulphite-reducing enzymes, which spread in the culture medium: the colonies of these spe­cies are surrounded by a black zone, sometimes with a metallic sheen. 

 

In use technique

Inoculate the material being examined onto the surface of the me­dium and incubate at 37°C for 48-72 hours; the development of black colonies permits a presumptive diagnosis of the genus. Ob­viously, this diagnosis must be confirmed with at least a microscopic test (fresh preparation cleared with lactophenol methyl blue: bran­ched pseudomycelium budding yeast cells, presence of chlamy­dospores, absence of ascospores) and the species must be iden­tified with currently used morphological, physiological or immunological tests.

 

User quality assurance (48 h-37°C)

 

Productivity control

C.albicans ATCC 60193: growth, brown metallic colonies

 

Selectivity control

E.coli ATCC 25922: inhibited

 

Storage

Dehydrated media: 15-30°C

User prepared plates: up to 7 days at 2-8°C

 

Reference

Nickerson V.J. (1953) J. Inf. Dis., 93, 43-56.

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