Piedraia hortae v1.1
Stroma on human hair, containing locules with asci and ascospores.
Stroma on human hair, containing locules with asci and ascospores.
Image Credit: Pedro Crous

Piedraia hortae (Piedraiaceae) is a non-pathogenic opportunist that infects human hair causing black piedra in humid tropical environments. The formation of dark, hardened nodules (hence piedra, stone) firmly attached to hair is symptomatic for the presence of P. hortae. This fungus is keratinolytic and forms its ascostromata within the nodules, where the ascospores are being produced. The anamorph is unknown. A second Piedraia species, P. quintanilhae, is known to infect the hair of chimpanzees. The superficial Piedraia infection causes hair break in immunocomprimised people as the hyphae penetrate cuticular layers and slowly degrade the cortex of the hair. Currently, there are no long term studies of infections of multiple fungal species in patients that have been affected by P. hortae. The genomic data of P. hortae will help us to estimate the biological and ecological potential of a fungus that limits itself to human hair as the sole substrate.


References.
De Hoog G. S., Guarro J., Gene J., Figuera M. J. (2000). Atlas of Clinical Fungi, second edition. Centraalbureau voor Schimmelcultures, Utrecht, NL.