[Contribution to the rapid diagnosis of yeast-forming fungi of clinical and hospital interest (author's transl)]

Abstract

Because the chlamydospore formation test for the identification of C. albicans is frequently utilized in most clinical Mycology laboratories, a comparative study of the different methods employed for the test was carried out. A total of 108 strains of yeast forming organisms belonging to C. albicans, C. tropicalis, C. stellatoidea, C. pseudotropicalis, C. parakrusei, C. guillermondii, C. neoformans, C. laurentii, C. albidus, C. candidum, T. glabrata, R. rubra, T. cutaneum, and S. carlsbergensis was used. The following culture media were compared: corn meal agar, rice agar, chlamydospore agar, PCB, and the recently described TOC medium (tween 80, oxgall and caffeic acid). Chlamydospore formation was positive, respectively, in 54.2%, 66.6%, 71.4%, 82.8%, and 91.4% and pseudomycelia formation, in 85.7%, 80%, 71.4%, 94.2%, and 91.4%. Only Cryptococcus neoformans produced in the TOC medium a characteristic coffee brown pigmentation which distinguished it from the other fungi. The results demonstrate the usefulness of the TOC medium in comparison with other culture media for the chlamydospore formation test for the diagnosis of C. albicans, and for the diagnosis of C. neoformans because of the characteristic pigmentation it produces.