Fungi can be divided into yeasts (eg Candida and Cryptococcus) and filamentous fungi or moulds (ie Aspergillus, Trichophyton and Alternaria). So fungi have more than one form being both yeasts and filamentous and are called ‘dimorphic’ (ie Histoplasma). Some fungi do not grow and have atypical forms such as Pneumocystis with so-called cysts and trophozoites (after parasite life forms). Identification of a fungus to genus level depends mostly on culture characteristics (colony appearance and microscopy), whereas species level identification usually requires biochemical or molecular testing.
Here we summarise what is known about the most common fungi infecting humans. Over 600 species of fungi have been linked with disease, but less than 30 species cause over 99% of infections. These are the focus of this website. For additional pathogenic fungi visit Mycology online.