Abstract
The neurotropism of the pathogenic dematiaceous fungi Fonsecaea pedrosoi, Cladosporium trichoides, Exophiala dermatitidis, Exophiala jeanselmei and Phialophora verrucosa was investigated using congenitally athymic nude (nu/nu) mice and their heterozygous (nu/+) littermates.
The first three species severely affected the brains of both mouse's strains while the latter two did not.
In the brains of both groups infected with F. pedrosoi, microabscesses with short hyphae appeared at an early stage of infection. Thereafter, in the nu/+ mice purulent lesions changed to granulomatous ones about 10 days after inoculation and hyphae were destroyed in the granulomas. In the nu/nu mice hyphae continued to grow and formed large purulent and necrotic lesions.
In the brains of the nu/+ and nu/nu mice inoculated with C. trichoides, microabscesses with slender hyphae appeared at an early stage of infection. As infection advanced, large purulent and necrotic lesions with abundant septated hyphae were formed in the nu/+ mice, while in the nu/nu mice slender septated hyphae grew freely without cellular responses.
In the E. dermatitidis infection microgranulomas with yeast-like cells were formed from day 4 on in the brains of both groups of mice. Even though the foci disappeared gradually by the 40th day in the nu/+ mice, a considerable number of them was counted in the nu/nu mice until the end of the experiment (62 days). Interestingly, acid mucopolysaccharide was stained around the yeast-like cells in the microgranulomas with alcian blue.
