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Scytalidium dimidiatum is a fungus found mainly in tropical and subtropical zones. Infection can cause a benign disease closely resembling dermatophytosis. In immunocompromised hosts, Scytalidium dimidiatum can also lead to phaehyphomycosis. Although awareness of these hyphae remains limited in developed countries, their incidence is growing due to increasing immigration and tourism. The rising incidence is well illustrated by three patients who presented onyxis and squamous-like manifestations on the arch of the foot upon returning from trips overseas and in whom various treatments were unsuccessful. In all three cases, culture in non-selective Sabouraud medium identified Scytalidium dimidiatum. These findings underline the need for laboratory testing before undertaking local or systemic treatment of onyxis especially since this pathogen can cause systemic disease. Study of ribosome genes showed that Scytalidium hyalinum is an homologous unpigmented mutant form of Scytalidium dimidatum. No antifungal agent has been effective for management of superficial manifestations and prevention depends mainly on the use of appropriate footwear in endemic areas.

Strains of different origins belonging to the two species of fungi imperfecti Cylindrocarpon ianothele and Calcarisporium arbuscula exhibit difference in their morphological or physiological appearances. We have attempted to determine if these variabilities could also be observed at the level of other phenotypic markers, the enzymes glucose-6-phosphate dehydrogenase, alcohol dehydrogenase, octanol dehydrogenase and malate dehydrogenase. Isozymes were separated by polyacrylamide gel electrophoresis and demonstrated isozyme variability as a function of growth and physiological states of a given strain. At the same state of development, the different strains exhibited highly heterogeneous isozyme groups which appear difficult to use for taxonomic purposes.

Purified beta-(1-3)-D-glucanases (from Aspergillus nidulans, Badidiomycetes sp. QM 806, Trichoderma viride) are used to release protoplasts from various yeasts. Two of them may prove taxonomic correlation. The enzyme of Basidomycetes sp. releases protoplasts from Ascomycetes, the enzyme of T. viride releases protoplasts from Ascomycetes and Heterobasidiomycetes; none of them acts on the Basidiomycetes.

The rigid structure of yeast cell wall may be a taxonomic criterion. Using the Helix pomatia juice (with mercaptoethylamine hydrochloride) as a polyenzymatic system, we have always obtained protoplasts from ascomycetous yeasts and never from basidiomycetous yeasts tested. Then, we have applied this enzymatic analysis to the Fungi imperfecti yeasts and, according to this test, separated genus looking like basidiomycetous behaviour: Trichosporon, Pityrosporum, Rhodotorula, Cryptococcus and non fermentative Candida (group II). Oppositely, we have put together the Fungi imperfecti yeasts looking like ascomycetous behaviour: Kloeckera, Trigonopsis, Brettanomyces and fermentative Candida (group I). With the second lytic system made of mercaptoethylamine-HCl and beta-(1-3)-D-glucanase, we have selected ascomycetous yeasts giving protoplasts: Saccharomycoidea with genus Saccharomyces, Kluyveromyces, Pichia, Hansenula, Citeromyces, Debaryomyces; we have joined Saccharomycodes and Hanseniaspora to this second group. The other ascomycetous yeasts studied did not give protoplasts with the definite lytic system made of purified beta-(1-3)-D-glucanase and thiol. These results seem to demonstrate that the structure of cell wall can act as an important taxonomic criterion.

The study of iconographical data and of six american and african strains of B. dermatitidis allows us to conclude that there are several discriminating characters between the members of the Blastomyces dermatitidis complex. The african strains are distinguished by the lack of sexual forms and old strains show the lost of the M lead to Y conversion. An identical character prevails among the strains of the two continents: tuberculate conidia which are obtained on corn meal agar. The authors are insisting on the identical characters encountered on Blastomyces and Histoplasma. All the mycotic strains described from cases of Gilchrist disease possess a Chrysosporium period. The experimental Gilchrist disease performed on rodents is more often obtained with members of the genus Chrysosporium.