Evaluating chromogenic candida agar for the identification of yeasts.

Abstract

The isolation of fungal pathogens has for many years relied upon the use of Sabouraud dextrose agar with chloramphenicol (SDC). In recent years, a range of chromogenic media has been made commercially available for the improved isolation and direct presumptive identification of fungal pathogens. Such media incorporate chromogenic enzyme substrates. Yeasts, assuming they have typical enzymatic behavior, cleave these chromogenic substrates to yield specific colony colours reflecting particular pathogenic groups. A methodology using chromogenic media, sometimes with adjunct biochemical tests aims to reduce the workload from fungal cultures, as it targets directly the presumptive identification of the most common fungal pathogens from the primary plate. Also, as a benefit to the patient, antifungal therapy can be started earlier. The Oxoid Candida Chromogenic agar, evaluated in this study, is as sensitive as SDC in isolating yeasts. lt is more rapid in identifying C. tropicalis and C. krusei. Moreover, it is very useful in recognizing mixed cultures. The costs of both methods are very similar.