Folliculitis decalvans is characterized by a persistent, abnormal subepidermal microbiota

Exp Dermatol. 2020 Mar;29(3):295-298. doi: 10.1111/exd.13916. Epub 2019 May 15.


Folliculitis decalvans (FD) is a chronic inflammatory disease of unknown aetiology. Although Staphylococcus aureus, frequently found on lesional skin, is thought to play a causal role, the importance of its involvement remains controversial. To examine the role of S aureus, we compared superficial and subepidermal microbiota in 20 FD patients who had S aureus on lesional skin and in 20 healthy controls using culture techniques and genomic identification, before and after an anti-staphylococcal treatment; we also screened for S aureus virulence factors. When present on lesional skin, S aureus colonized non-lesional and subepidermal skin in 80% of cases. These data imply a break in the epidermal barrier integrity and that an abnormal non-lesional skin microbiota persists in FD. S aureus had no superantigenic toxin in 31% of cases and no toxin specificity. Clinical improvement obtained in most cases upon treatment was associated with the disappearance of S aureus in all studied areas, with an incomplete restoration of normal microbiota and a significant increase in negative bacterial samples. This persistent unbalanced, subepidermal microbiota may act as a reservoir of abnormal flora and explain the chronicity of FD, suggesting new avenues of research to restore normal microbiota.

Trial registration: NCT02157688.

Keywords: Cutibacterium acnes; Staphylococcus aureus; folliculitis decalvans; scalp microbiota; subepidermal microbiota.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria
  • Case-Control Studies
  • Dysbiosis
  • Epidermis / immunology
  • Epidermis / microbiology
  • Folliculitis / metabolism*
  • Folliculitis / microbiology*
  • Genome, Bacterial
  • Genomics
  • Humans
  • Inflammation
  • Microbiota
  • Skin / immunology
  • Skin / microbiology*
  • Skin / pathology
  • Staphylococcus aureus / metabolism*
  • Superantigens
  • Virulence Factors


  • Superantigens
  • Virulence Factors

Associated data