title: Identification of Malassezia species in patients with seborrheic dermatitis in China.
abstract: BACKGROUND
  The causes of seborrheic dermatitis (SD) are complex and incompletely understood. Among the factors, Malassezia yeasts have been reported to play a major etiological role in SD. Many previous studies adopted conventional culture methods that were disadvantaged to detect Malassezia microflora in SD patients, resulting in a low detection rate for each species and high variance in types of microflora observed.
  
  
  OBJECTIVE
  This study analyzed Malassezia microflora in SD patients by applying a transparent dressing to the lesional skin and using direct detection of fungal DNA using nested PCR.
  
  
  METHODS
  We collected samples from the lesional skin of 146 SD patients in China and extracted fungal DNA directly from the lesional samples without culture. Specific primers for each Malassezia species were designed to amplify existing yeasts in each sample. Some samples were randomly selected to culture and identified by morphological and physiologic criteria.
  
  
  RESULTS
  M. globosa and M. restricta were found in 87.0 and 81.5% of seborrheic dermatitis patients, respectively, which together accounted for more than 50% of Malassezia spp. recovered in these Chinese patients. The majority of SD patients (82.9%) showed co-colonization of two or more Malassezia species.
  
  
  CONCLUSIONS
  M. globosa and M. restricta predominated in Malassezia colonization in Chinese SD patients. Compared with conventional culture, non-culture-based methods may more accurately reflect Malassezia microflora constitution.
authors.affiliation: Department of Dermatovenerology, West China Hospital, Sichuan University, Chengdu, People's Republic of China. dr.zhanghao@126.com
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Yuping
authors.initials: Y
authors.lastname: Ran
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xie
authors.forename: Ruifeng
authors.initials: R
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D012628:Dermatitis, Seborrheic / Q000453:epidemiology* / Q000382:microbiology*; D003881:Dermatomycoses / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D008290:Malassezia / Q000302:isolation & purification*; D008297:Male; D008828:Microbiological Techniques / Q000379:methods; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D015995:Prevalence; D055815:Young Adult
chemical_list: D017931:DNA Primers; D004271:DNA, Fungal