Use of a commercial reagent leads to reduced germ tube production by Candida dubliniensis

The goal of this study was to determine the factor(s) explaining our inability to detect Candida dubliniensis. When germ tube-positive yeasts were tested for C. dubliniensis, no C. dubliniensis was detected; however, 58 C. dubliniensis strains were detected when germ tube-negative Candida albicans strains were tested further. Since all 58 C. dubliniensis strains detected were germ tube negative, these data implied that false-negative germ tube tests occurred with germ tube solution (GTS; Remel, Lenexa, KS). All 41 known C. dubliniensis strains tested were negative with GTS, whereas 40 were positive with rabbit serum (RS; Sigma-Aldrich, St. Louis, MO). Results for C. albicans were equivalent in GTS and RS. In conclusion, GTS cannot be used for the detection of C. dubliniensis, and switching from yeast to hyphae in C. dubliniensis is more restricted than in C. albicans.