BiGGY AGAR

Code: CM0589

For the isolation and presumptive identification of Candida species

Typical Formula*	gm/litre
Yeast extract	1.0
Glycine	10.0
Glucose	10.0
Sodium sulphite	3.0
Bismuth ammonium citrate	5.0
Agar	13.0
pH 6.8 ± 0.2 @ 25°C

* Adjusted as required to meet performance standards 

Directions
Suspend 42g in 1 litre of distilled water and bring gently to the boil to dissolve the agar. Allow to cool to 50-55°C. Mix gently to disperse the flocculant precipitate and pour into sterile Petri dishes.
DO NOT AUTOCLAVE THE MEDIUM.

Description
BiGGY, Bismuth Sulphite Glucose Glycine Yeast Agar, is based on the formulation developed by Nickerson¹ and may be used for the isolation and presumptive identification of Candida species.

In a study of sulphite reduction by yeasts, the ability of many yeasts to reduce a bismuthyl hydroxy polysulphite was noted. This was demonstrated to be most evident in Candida species. but strong reducing ability was confined to Candida albicans, Candida krusei and Candida tropicalis. Growth on an acidic or neutral medium containing bismuth sulphite produced black colonies because of the extra-cellular reduction of the bismuth sulphite, to bismuth sulphide.

The bismuth sulphite complex confers a high degree of selectivity to the medium, and most strains of bacteria are inhibited on BIGGY Agar.
Barr and Collins² described the addition of neomycin sulphate to the medium at 2mg per litre to improve inhibition of accompanying bacterial flora.

The medium may be used for the isolation and presumptive identification of Candida albicans and Candida tropicalis from sputum^2,3 and vaginal smears⁴. It is a recommended medium for the quality assessment of pharmaceutical and cosmetic products⁵.

Technique
Reconstitute the medium as directed and pour into sterile Petri dishes to contain approximately 20ml of medium.
Freshly prepared plates should be used. Reactions on slant cultures are unsatisfactory¹.
Incubate the plates at 28-30°C and examine daily for evidence of sulphite reduction.