CANDIDA BCG AGAR BASE

Candida albicans is most frequently isolated from clinical specimens. Species of Candida, other than C. albicans are normal flora of cutaneous and mucocutaneous surfaces and are only rarely incriminated as agents of clinical disease. Of the many media used for isolating and differentiating Candida, Pagano Levin Base employes TTC (Triphenyl Tetrazolium Chloride) as an indicator. Harold and Snyder observed that the TTC used greatly retards the growth of some Candida species, while completely inhibiting the rest. Therefore, to overcome this difficulty, they formulated Candida BCG Agar, which employs bromocresol green instead of TTC as the indicator. Candida BCG Agar Base is used to obtain pure yeast colonies from mixed cultures on the basis of colony morphology.
Selectivity is obtained by the addition of neomycin. Neomycin is incorporated to inhibit gram-negative bacteria and some gram-positive bacteria. Neomycin is an aminoglycoside antibiotic that is active against aerobic and facultatively anaerobic gram-negative bacteria and certain gram-positive bacteria. Bromocresol green is the indicator. Acid production due to fermentation lowers the pH of the medium and subsequently the colour of medium changes to yellow, indicated by yellow zones around the dextrose-fermenting colonies. C.albicans appears as blunt conical colonies with smooth edges and yellow to blue green colour. Other Candida species appear as smooth to rough colonies, with either convex or cone shaped colonies. Standard methods should be followed for inoculating the plates of Candida BCG Agar. Presumptive Candida colonies should be further identified by gram staining, biochemical and serological testing.

for primary isolation and identi?cation of Candida species