New Yeast Species, Malassezia dermatis , Isolated from Patients with Atopic Dermatitis

Abstract

Malassezia species are considered to be one of the exacerbating factors in atopic dermatitis (AD). During examination of the cutaneous colonization of Malassezia species in AD patients, we found a new species on the surface of the patients' skin. Analysis of ribosomal DNA sequences suggested that the isolates belonged to the genus Malassezia. They did not grow in Sabouraud dextrose agar but utilized specific concentrations of Tween 20, 40, 60, and 80 as a lipid source. Thus, we concluded that our isolates were new members of the genus Malassezia and propose the name Malassezia dermatis sp. nov. for these isolates.Malassezia species are known causative factors in pityriasis versicolor, seborrheic dermatitis (SD), and atopic dermatitis (AD) (3). In the last decade, research has focused primarily on isolating Malassezia strains and detecting specific immunoglobulin E (IgE) antibodies from patients (9,13,14,26). A comparison of the isolation rates of Malassezia species from the skin of AD patients and healthy control subjects detected a significantly higher rate for patients than for healthy subjects (8). AD patients had specific IgE antibodies against Malassezia, while healthy subjects did not. In recent years, studies have increasingly been directed towards analyzing how the cutaneous microflora at the species level are related to each disease type (pityriasis versicolor, SD, and AD) (1,6,7,12,16). We previously compared the distribution of Malassezia species in skin lesions of AD patients and in healthy subjects using a nonculture method (nested PCR) that is not affected by the isolating medium (21). Of the seven members of the genus Malassezia, Malassezia globosa and M. restricta were the species most commonly associated with AD, while M. obtusa and M. pachydermatis were not detected in AD. In our survey of cutaneous Malassezia microflora, we isolated new Malassezia species from several patients with AD. In this paper, we propose a new species, M. dermatis, for these isolates. MATERIALS AND METHODSMalassezia isolates. Nineteen AD outpatients at Juntendo University Hospital were included in the study. To obtain samples, OpSite transparent dressings (3 by 7 cm; Smith and Nephew Medical Ltd., Hull, United Kingdom) were applied to skin lesions (erosive, erythematous, and lichenoid) on the scalp, back, and nape of the neck of AD patients. Samples were then transferred onto Leeming and Notman agar (LNA) (10.0 g of polypeptone, 5.0 g of glucose, 0.1 g of yeast extract, 8.0 g of ox gall, 1.0 mg of glycerol, 0.5 g of glycerol stearate, 0.5 mg of Tween 60, 10 ml of cow's milk [whole fat], and 12.0 g of agar per liter) plates containing 50 l of chloramphenicol (Sankyo, Tokyo, Japan) and incubated at 32°C for 2 weeks.Direct DNA sequencing of rRNA genes of the isolates. Yeast isolates recovered from LNA medium were identified by analysis of rRNA gene sequences. Nuclear DNA of the isolates was extracted by the method of Makimura et al. (15). The D1 and D2 regions of 26S ribosomal DNA (rDNA) and internal transcribed spacer (IT...

Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals

“…Nucleotide sequence analysis of the 26S rDNA (D1/D2 regions) of these isolates showed fewer than five substitutions over 577 bp among them; the isolates differed by >23 substitutions over 577 bp from the eight Malassezia species that have been reported previously (Fell et al, 2000;Sugita et al, 2002). The difference between these isolates and the eight Malassezia species exceeded that generally observed between species (Scorzetti et al, 2002).…”

“…Recently, an eighth species of Malassezia, newly isolated from the skin of a human with atopic dermatitis, was described as Malassezia dermatis by using molecular analysis (Sugita et al, 2002). As a result of molecular analysis, we suggested that an isolate from a cat might belong to a novel species of the genus Malassezia (Hirai et al, 2002).…”

“…Morphological and physiological characteristics of the five isolates were similar in many ways to those of M. sympodialis and M. dermatis (Guého et al, 1996;Sugita et al, 2002); however, the isolates can be distinguished from these two species by their inability to use Cremophor EL as the sole lipid source and to hydrolyse aesculin (Table 2). In terms of morphology, cells were comparatively small (1?5-2?062?5-3?0 mm) (Guého et al, 1996).…”

Especies de Malassezia aisladas de pacientes con lesiones dermatológicas

“…Recently, other new Malassezia species have been reported, namely M. japonica (21) and M. dermatis (22), and these may be similar to some of the unclassified species referred above.…”

“…New questions have been raised about the significance and relationships of the Malassezia species in clinical infections (1,4), this is due to factors such as the recent description of new species (2,21,22), the isolation of Malassezia as part of the microbial community of human skin rich in sebaceous glands (1,2,6,16), and the variability in colonization according to different age groups and sebaceous glands activity (15,19,23).…”