Facial Skin Microbiome in Patients With Moderate-to-Severe Acne Vulgaris Treated With Isotretinoin

Acne vulgaris is associated with changes in the facial skin microbiome, but longitudinal microbiome changes during isotretinoin therapy remain incompletely understood. This prospective observational cohort study aims to characterize the facial skin microbiome in patients with moderate-to-severe acne vulgaris before and during isotretinoin treatment and to compare microbiome profiles with healthy individuals. Participants with moderate-to-severe acne vulgaris receiving standard-of-care oral isotretinoin will be followed prospectively. Facial skin swab samples will be collected before treatment and at scheduled follow-up visits during therapy. Healthy volunteers without acne will provide a single facial skin swab for comparison. Bacterial communities will be analyzed using 16S rRNA gene sequencing, and clinical severity will be assessed using validated acne severity scores and lesion counts. The study will evaluate changes in microbial diversity, bacterial composition, and the relative abundance of acne-associated microorganisms during isotretinoin treatment. Associations between microbiome changes and clinical improvement will also be explored. Results are expected to improve understanding of the role of the skin microbiome in acne and provide evidence for future microbiome-based therapeutic strategies.

Inclusion Criteria: Acne Vulgaris Cohort: * Participants aged 16-35 years. * Clinical diagnosis of acne vulgaris. * Presence of acne lesions on both cheeks. * Indication for oral isotretinoin treatment according to clinical assessment at Can Tho University of Medicine and Pharmacy Hospital. * Willingness to participate in the study. Healthy Control Cohort: * Voluntary participation in the study. * No history or clinical manifestations of acne vulgaris. * No use of antibiotics or isotretinoin within the previous 6 months. * No lesions of other skin diseases on the face. Exclusion Criteria: * Current dermatologic diseases such as rosacea, contact dermatitis, eczema, or psoriasis. * Current acute or chronic medical diseases. * Use of antibiotics or isotretinoin within the previous 3 months. * Use of phototherapy or topical probiotics on the facial skin within the previous 3 months. * Use of facial cleansing products or topical medications within 24 hours before sample collection. * History of allergy. * Unwillingness to participate in the study.