Folliculitis decalvans is characterized by a persistent, abnormal subepidermal microbiota

Area of Science:

• Dermatology
• Microbiology
• Inflammatory Diseases

Background:

• Folliculitis decalvans (FD) is a chronic scalp condition of unknown cause.
• Staphylococcus aureus is frequently found on lesional skin, but its causal role is debated.

Purpose of the Study:

• To investigate the role of S. aureus in FD by comparing skin microbiota in patients and controls.
• To assess the impact of anti-staphylococcal treatment on microbiota and clinical outcomes.

Main Methods:

• Compared superficial and subepidermal microbiota in 20 FD patients and 20 controls using culture and genomic methods.
• Screened for S. aureus virulence factors before and after treatment.
• Evaluated clinical improvement post-treatment.

Main Results:

• S. aureus colonized non-lesional and subepidermal skin in 80% of FD patients, suggesting epidermal barrier breakdown.
• S. aureus lacked superantigenic toxins in 31% of cases, with no specific toxin profile.
• Treatment led to S. aureus disappearance and clinical improvement, but incomplete microbiota restoration.

Conclusions:

• Persistent, unbalanced subepidermal microbiota may act as a reservoir for abnormal flora in FD.
• This persistent dysbiosis could explain the chronic nature of folliculitis decalvans.
• Restoring normal skin microbiota presents a potential therapeutic avenue for FD.