Comparison of four commercially available chromogenic media to identify Candida albicans and other medically relevant Candida species.

BACKGROUND

The number of invasive Candida infections has significantly increased in recent decades. For the successful treatment of fungal infections, rapid identification at the species level, particularly in polyfungal infections, is a key factor. In this study, four commercially available chromogenic media, CandiSelect™ 4 (CS4), chromID™ Candida Agar (CCA), BBL™ CHROMagar™ Candida Medium (BBL) and Brilliance™ Candida Agar (BCA) were evaluated for Candida identification.

MATERIAL/

METHODS

Overall, 181 bronchial secretion samples from intensive care patients were analysed prospectively. In addition, 18 primarily sterile materials, previously tested positive for Candida, were investigated retrospectively. All samples were cultured as recommended by the manufacturer and visually inspected after 24 and 48 hours by three independent investigators. As a control, colonies were identified by MALDI-TOF MS. Specificity and sensitivity were determined for C albicans identification prospectively.

RESULTS

CS4 and BCA showed the best overall consensus with the identification results reached by MALDI-TOF MS for Candida albicans and species. A clear differentiation between the species could be ascertained via easily identifiable, species-specific coloration in contrast to BBL and CCA. Sensitivity for C albicans (n = 73) identification varied between 32% (BCA) and 69% (CS4 and CCA) after 24 hours and 68% (BBL) and 82% (BCA) after 48 hours incubation, while specificity ranged between 62% (BBL) and 81% (CCA) after 24 hours and 82% (BBL) and 85% (CS4) after 48 hours.

CONCLUSION

CS4 and BCA are recommended for routine identification of Candida species in human samples.