Dermatomycoses: from head to toe
A definitive classification is not possible until the perfect stage has been identified and described. The classification is arranged in six groups (see table), three of which are relevant to disorders in human beings.
The last group, Fungi Imperfecti, is a group with no identified sexual reproduction and whose perfect stage is therefore unknown.
The actinomycetes are gram-positive bacteria which cause, inter alia, pseudomycoses.
Of all the known species of fungus, only a few are pathogenic. Furthermore, the presence of such a fungus in or on the human body does not automatically mean that there is mention of pathology. The presence of Candida spp., for example, can be demonstrated in human faeces without there being any question of an infection. Fungi are therefore not inevitably pathogenic. The truth of this statement is underlined by the increasing number of immuno-compromised patients. AIDS, transplantations and chemotherapy can lead to reduced immune system function. Precisely at times such as these, fungi seize their opportunity and launch an attack. At first sight the result may appear to be a harmless case of thrush, but it may also be a systemic infection which is difficult to treat, such as a disseminated Aspergillus infection, sometimes with a fatal outcome.
Disorders caused by fungi are called mycoses. They are usually classified according to the site where they appear. There is a large group of disorders which affect the skin. Many fungi, such as the dermatophytes, go no deeper than the horny layer of the skin: these are the superficial infections. When fungi are also demonstrated deeper in the tissues, these are referred to as subcutaneous infections. If organic systems or organs are affected, they are called systemic infections. It will be obvious that the latter group is the most life-threatening. In terms of frequency, however, systemic fungal infections are the rarest.