Distinct skin microbiome modulation following different topical acne treatments in mild acne vulgaris patients: a randomized, investigator-blinded exploratory study.

The effects of topical non-antibiotic acne treatment on skin microbiota have rarely been demonstrated. In the study, we randomized 45 mild acne vulgaris participants into 3 treatment groups, including a cream-gel dermocosmetic containing Aqua Posae Filiformis, lipohydroxy acid, salicylic acid, linoleic acid, niacinamide and piroctone olamine (DC), retinoic acid 0.025% cream (VAA), and benzoyl peroxide 2.5% gel (BP). At months 0, 1 and 3, skin specimens were swabbed from the cheek and forehead and sequenced by targeting V3-V4 regions of the 16S rRNA gene. QIIME2 was used to characterize bacterial communities. Acne severity, sebum level, and tolerability were assessed concomitantly in each visit. We found that both VAA and BP could significantly reduce the bacterial diversity at month 1 (P-value=0.010 and 0.004, respectively), while no significant reduction was observed in DC group. The microbiota compositions also significantly altered for beta diversity in all treatments (all P-value=0.001). An increased Cutibacterium with decreased Staphylococcus relative abundance was observed at month 1 and 3 in DC group, while an opposite trend was demonstrated in VAA and BP groups. These findings suggest a potential impact of DC, VAA, and BP on the diversity and composition profiles of the skin microbiota in mild acne participants.