Causes
The infection with the most common Candida species is primarily an infection with Candida albicans. This is by far the most common species worldwide. As normal inhabitants they colonize skin and in most cases also the mucous membranes of the human body.
In this state, they do not pose a direct danger to the body, but fulfill important functions in a complex system of bacteria and fungi. If the microbial milieu on the skin and mucous membranes is out of balance (for example, due to an immune deficiency), Candida albicans can transform into a hyphal form and migrate into deeper tissues. Once there, an infectious process often develops.
If this can be limited superficially and locally, it is called candidiasis. If it manifests itself on the skin and mucous membranes, the familiar picture of a mucocutaneous candidosis or thrush can be observed. If the immune system is very much weakened, the pathogen can spread multilocally in the blood and organ system and ultimately lead to systemic mycosis.
The less known species Cryptococcus can be divided into the pathogens Cryptococcus neoformans and Cryptococcus gattii. The associated clinical picture is called cryptococcosis. The pathogens mentioned are usually found on grasses and other plants.
Especially the pathogen Cryptococcus gattii can be found in tropical regions.If the pathogens enter the gastrointestinal tract of birds (especially pigeons) after ingestion through their diet, they can initially multiply in a suitable environment. Humans become infected with the pathogens primarily through the excrement excreted by the birds or the contaminated dust of excrement products of the birds. In most cases, cryptococcus infections initially infect the lungs. Massive immune deficiency can also lead to a manifestation of the brain or meninges (meningoencephalitis). Massive immunodeficiency occurs mainly in autoimmune diseases, such as AIDS.
How does the doctor recognize a yeast infection?
Infections caused by the different types of yeast fungi are generally diagnosed using different methods. In case of an infection with Candida albicans, a microscopic examination is the first diagnostic method to be considered. The level of examination can be improved by using optical brighteners or silver staining (Grocott).
Nowadays, MALDI-TOF mass spectrometry is also increasingly used after previous culture. In this method, the proteins contained in the bacteria are separated and differentiated by a pinpoint ion bombardment. It is also possible to examine mannan or glucan antigens, which can be specifically assigned to Candida species.
This diagnostic test is usually performed from a sample in blood serum or bronchoalveolar lavage (BAL). The diagnostic phase is very similar in the case of a cryptococcus infection. Here, fine methods such as microscopy, PCR or, as mentioned above, antigen detection from the patient’s serum are used.
