title: Distribution of Malassezia species on the skin of patients with atopic dermatitis, psoriasis, and healthy volunteers assessed by conventional and molecular identification methods.
abstract: BACKGROUND
  The Malassezia yeasts which belong to the physiological microflora of human skin have also been implicated in several dermatological disorders, including pityriasis versicolor (PV), atopic dermatitis (AD), and psoriasis (PS). The Malassezia genus has repeatedly been revised and it now accommodates 14 species, all but one being lipid-dependent species. The traditional, phenotype-based identification schemes of Malassezia species are fraught with interpretative ambiguities and inconsistencies, and are thus increasingly being supplemented or replaced by DNA typing methods. The aim of this study was to explore the species composition of Malassezia microflora on the skin of healthy volunteers and patients with AD and PS.
  
  
  METHODS
  Species characterization was performed by conventional, culture-based methods and subsequently molecular techniques: PCR-RFLP and sequencing of the internal transcribed spacer (ITS) 1/2 regions and the D1/D2 domains of the 26S rRNA gene. The Chi-square test and Fisher's exact test were used for statistical analysis.
  
  
  RESULTS
  Malassezia sympodialis was the predominant species, having been cultured from 29 (82.9%) skin samples collected from 17 out of 18 subjects under the study. Whereas AD patients yielded exclusively M. sympodialis isolates, M. furfur isolates were observed only in PS patients. The isolation of M. sympodialis was statistically more frequent among AD patients and healthy volunteers than among PS patients (P < 0.03). Whether this mirrors any predilection of particular Malassezia species for certain clinical conditions needs to be further evaluated. The overall concordance between phenotypic and molecular methods was quite high (65%), with the discordant results being rather due to the presence of multiple species in a single culture (co-colonization) than true misidentification. All Malassezia isolates were susceptible to cyclopiroxolamine and azole drugs, with M. furfur isolates being somewhat more drug tolerant than other Malassezia species.
  
  
  CONCLUSIONS
  This study provides an important insight into the species composition of Malassezia microbiota in human skin. The predominance of M. sympodialis in both normal and pathologic skin, contrasts with other European countries, reporting M. globosa and M. restricta as the most frequently isolated Malassezia species.
authors.affiliation: Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, I, Miecznikowa 1, 02-096 Warsaw, Poland. t.jagielski@biol.uw.edu.pl.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Jagielski
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Rup
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ziółkowska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Roeske
authors.forename: Anna B
authors.initials: AB
authors.lastname: Macura
authors.forename: Jacek
authors.initials: J
authors.lastname: Bielecki
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004271:DNA, Fungal / Q000032:analysis; D003876:Dermatitis, Atopic / Q000382:microbiology*; D003881:Dermatomycoses / Q000382:microbiology*; D005260:Female; D006801:Humans; D008290:Malassezia / Q000187:drug effects / Q000302:isolation & purification*; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods; D008969:Molecular Sequence Data; D009172:Mycology / Q000379:methods; D016133:Polymerase Chain Reaction / Q000379:methods; D011565:Psoriasis / Q000382:microbiology*; D012867:Skin / Q000382:microbiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D004271:DNA, Fungal