CHARACTERIZATION OF A POTENTIAL NEW MALASSEZIA SPECIES ISOLATED FROM HELTHY HUMAN SKIN

Luciana Campos Paulino (UFABC); Nicholas Cassai (NY Harbor Healthcare); Philip Tierno (NYU Medical Center); Martin Blaser (New York University)

The genus Malassezia comprises lipophilic yeasts that are members of the residential cutaneous microbiota of humans and other warm-blooded animals, but also have been associated with skin conditions including pityriasis versicolor, seborrheic dermatitis, dandruff, atopic dermatitis, folliculitis, and psoriasis. For many years, these diseases were attributed exclusively to one species, M. furfur, but recently this concept has been overturned due in part to advances in methodologies for studying these organisms. Since 1990, the taxonomy of the genus Malassezia has undergone many revisions. The recent interest in studying this genus, associated with the improvement of methodologies, has contributed to the description of six new species in the past six years.  Our previous studies using clone library analysis and quantitative multiplex real-time PCR revealed the presence of a Malassezia organism distinct from the currently recognized species in most skin samples from healthy subjects and patients with psoriasis. We now have cultivated Malassezia organisms from 57 skin samples to isolate and characterize this organism on the basis of a multiphasic approach, as well as to compare it to known Malassezia species. The distinct organism was cultured from healthy human forehead skin. Phylogenetic analyses based on 5.8S rDNA and internal transcribed spacer regions (ITS1 and ITS2) revealed it is most closely related to M. restricta; however, it belongs to a distinct group, suggesting that it could represent a novel Malassezia species. Moreover, the ITS1 and ITS2 sequence identities between M. restricta and the distinct organism is considerably lower comparing to the identity within M. restricta species. This organism resembles M. restricta in several morphological and physiological aspects, and is very fastidious and could not be maintained in vitro.