Dysbiosis in Acne Vulgaris and Hidradenitis Suppurativa: A Comparative Microbiome Analysis.

Acne and hidradenitis suppurativa (HS) are inflammatory disorders of the pilosebaceous unit that exhibit distinct clinical manifestations, indicating that they likely differ in their underlying pathophysiology. Microbial dysbiosis is implicated in both diseases, yet direct comparisons using unified methods and analyses incorporating the oral microbiome are lacking. In this study, we collected lesional and nonlesional skin, buccal mucosa and faecal samples from 28 HS patients, 29 acne patients and 40 healthy controls, and profiled microbial communities using 16S rRNA V3-V4 sequencing with qPCR validation. HS lesions showed a pronounced enrichment of anaerobic Gram-negative taxa, including Prevotella, Porphyromonas and Fusobacterium, whereas acne lesions were dominated by Cutibacterium and Pseudomonas. Oral microbiome diversity was increased in both diseases, with HS showing distinct enrichment of Prevotella and Veillonella. HS patients also exhibited reduced gut microbial diversity. Correlation analyses revealed coordinated microbial alterations across the oral-gut-skin axis, and qPCR confirmed elevated concentrations of key anaerobes in HS. By directly comparing acne and HS across multiple anatomical sites, our study helps differentiate general inflammatory microbiome changes from those more specific to HS. The findings also suggest a potential oral-gut-skin microbial axis that may contribute to the chronic and destructive phenotype of HS, providing insights that could inform future microbiome-targeted therapeutic approaches.