Morphologic and physiologic characteristics of Costa Rica pathogenic fungi (Dermatiaceae)]

Forty one strains of dematiaceous fungi from the Mycology collection of the University of Costa Rica were studied. Thirty three were pathogenic (Fonsecaea pedrosoi, Cladosporium carrionii, Xylohypha bantiana, Exophiala jeanselmei, Rhinocladiella aquaspersa, Phialophora verrucosa) and the other eight were contaminants (Hormodendrum sp.). Morphological studies were done using the slide culture technique. The physiological criteria used were: urease production, gelatin and Loeffler media liquefaction; xanthine, tyrosine, starch and casein hydrolysis; nitrate utilization; carbohydrate uptake; sensitivity to cycloheximide and thermotolerance in glucose-Sabouraud medium. The physiological tests did not provide characteristic patterns for the different genera of pathogenic fungi, even though these differences were detected in non pathogenic fungi; the tests may be useful for the quick separation of both groups. Physiological test may have a limited value in the identification of fungi and the morphological analysis cannot be substituted by physiological studies.