Identification of Malassezia pachydermatis from healthy and diseased human skin.
Malassezia pachydermatis is the only species in the genus Malassezia that is classically considered to be zoophilic. This yeast is only occasionally isolated from human skin, although it has been found to cause septic epidemics, especially in neonates. The aim of our study was to investigate the prevalence of M. pachydermatis on the skin of patients with Malassezia-associated diseases and of healthy subjects. One hundred and sixty skin scrapings from patients with pityriasis versicolor (PV), seborrhoeic dermatitis (SD), psoriasis (PS) and healthy individuals, forty each, were inoculated into Sabouraud dextrose agar and into modified Dixon agar. The yeasts isolated were identified according to their macroscopic and microscopic features and physiological properties. M. globosa was the most commonly isolated species in lesional skin of PV (65%) and PS (55%), M. restricta in lesional skin of SD (27.5%), while M. sympodialis was the predominant species recovered from healthy skin, representing 30% of the isolates. Zoophilic species, M. pachydermatis was identified in only one case, from the lesional skin of SD. The results of our study confirm that M. pachydermatis is not a member of the normal human flora and its presence on human skin is rare and indicates transmission from an external source.