ARS | Publication request: Production of White Colonies on CHROMagar Candida(TM) by Members of the Candida glabrata Clade and Other Species with Overlapping Phenotypic Traits

Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 29, 2008
Publication Date: October 1, 2008
Citation: Bishop, J.A., Chase, N., Kurtzman, C.P., Merz, W.G. 2008. Production of White Colonies on CHROMagar Candida(TM) by Members of the Candida glabrata Clade and Other Species with Overlapping Phenotypic Traits. Journal of Clinical Microbiology. 46(10):3498-3500.

Interpretive Summary: Clinical mycologists often use selective agar media for rapid identification of pathogenic yeasts. A medium designated CHROMagar Candida incorporates dyes that give colors specific to certain pathogenic yeasts. However, results from the Johns Hopkins Clinical Mycology Laboratory suggested that isolates of some species did not react as expected. These isolates were identified from gene sequence analysis and the correlation with reactions on the dye-containing medium showed that some of the pathogenic yeasts gave unexpected color reactions, thus presenting incorrect identifications. This research further demonstrates that commonly used growth tests may be unreliable for species identification and that gene sequence analysis is the preferred method when treatment of mycotic infections requires specific antibiotics.

Technical Abstract: We hypothesized that species of the Candida glabrata clade and species with phenotypic traits overlapping with C. glabrata would produce white colonies on CHROMagar Candida. Of 154 isolates (seven species) tested, C. bracarensis, C. nivariensis, C. norvegensis, C. glabrata, and C. inconspicua produced white colonies; the Pichia fermentans group and C.krusei did not. Many of these species are difficult to identify phenotypically; white colonies may signal the need for molecular approaches.