Purpose of the study: The goal of the study was to evaluate the practical value of rapid tests in laboratory diagnostics of pathogenic yeasts with focus on Candida albicans and to elaborate an alternative method of germ tube test in NYP medium.
Material and methods: 200 clinical strains of 12 yeast species isolated in mycology laboratory at the Department of Clinical Microbiology, Teaching Hospital in Hradec Králové were investigated. All these isolates were studied according to their growth onto the two chromogenic media (CandiSelect, Bio-Rad, HiCrome Candida Agar, HiMedia) and the production of germ tubes in serum and NYP medium. The results of identification by the rapid tests were verified by standard methods.
Results: All 100 C. albicans isolates grew on CandiSelect as well as HiCrome Candida agar as characteristically coloured colonies. In case of HiCrome Candida agar, C. tropicalis strains (n = 15) produced typically blue-green colonies. Sensitivity and specifity of both the media was 100%. Germ tubes were observed in serum and NYP medium in all C. albicans strains. Lower proportion of pseudohyphae was noticed in NYP medium than serum particularly in non-albicans Candida strains. Two strains C. tropicalis (13.3 %) produced germ tubes in serum, but not NYP.
Conclusions: Both CandiSelect and HiCrome Candida Agar identified reliably C. albicans isolates, in case of the latter C. tropicalis as well. The comparison of the production of germ tubes in serum versus NYP medium showed comparable results and lower risk of false positive results in NYP medium which can follow from pseudohyphae formation. All rapid tests studied represent reliable tools for presumptive identification of C. albicans.