The oomycete Pythium oligandrum can suppress and kill the causative agents of dermatophytoses

Pythium oligandrum is known for its strict mycoparasitism against more than 50 fungal and oomycete species including some of its close relatives. However, the ability of this oomycete (peronosporomycete) to suppress and kill the originators of dermatophytoses in animals and humans has not been systematically studied. Here we provide biological and molecular evidence that the most common originators of clinically important dermatophytoses belonging to the genera Trichophyton, Microsporum, Nannizzia and Epidermophyton are efficiently suppressed and killed by Pythium oligandrum to 50–100 % on the individual examined test agar plates. A significant intra- and interspecies variability was noted. Molecular analysis of the gene expression profiles for selected genes of both Pythium oligandrum and Microsporum canis provided an understanding of the agar plates observations regarding the sequence of activation of the aggressivity genes in both the parasite and the killed species. Agar plate and suspension experiments revealed that the average time needed for the killing of the dermatophyte by the oomycete was between 48 and 72 h after the contact. The potential for practical use of these findings is demonstrated by results obtained for patients with foot mycoses having both acute and recurrent infections.