Ultrastructural changes produced by ketoconazole in the yeast-like phase of Paracoccidioides brasiliensis and Histoplasma capsulatum.

The ultrastructural changes produced by ketoconazole in the yeast-phase of H. capsulatum and P. brasiliensis were studied by means of scanning and transmission electron microscopy. The observed alterations on both fungi were very similar to those induced by the same drug on the ultrastructure of C. albicans. These alterations include surface changes, abnormal membrane proliferation, fatty degeneration of the cytoplasm and lysis of the subcellular organelles. P. brasiliensis seems to be more sensitive to ketoconazole than H. capsulatum, since the necrosis of most of the cells was obtained in the former at a concentration of 0.1 microgram/ml and in the latter at 1 microgram/ml.