[Host-pathogen relations in yeasts].

Allogenic and autogenic factors are decisive for a colonization of warmblooded hosts by yeasts where they can live inside as symbiont, commensal or pathogen. To develop pathogenicity a capacity of yeasts for multiplication inside of humans or homoiothermic animals and resistance to environmental influences is not sufficient. Pathogenicity rather depends on the ability of structural morphological changes, phenomena of adherence and of microbial competition as well as the presence of genes for down-regulation of the host defense and for enzyme production enabling a parasitic life style. Among the yeasts Cryptococcus neoformans and some Candida species meet these requirements.