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

Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit and is one of the most common dermatologic disorders worldwide. Increasing evidence suggests that acne is associated with alterations in the composition and diversity of the skin microbiome rather than the presence of a single pathogenic microorganism. However, longitudinal changes in the facial skin microbiome during isotretinoin treatment have not been fully characterized in Southeast Asian populations.

This study is a prospective observational cohort conducted in Vietnam. The study includes two participant groups: patients with moderate-to-severe acne vulgaris and healthy volunteers without acne. Patients receive oral isotretinoin according to routine clinical practice and institutional treatment protocols. The study does not assign or modify treatment; investigators prospectively observe clinical and microbiome changes during routine care.

Facial skin samples are collected using standardized skin swab procedures from predefined facial sites. Samples are processed for bacterial DNA extraction and 16S rRNA gene sequencing to characterize microbial communities. Sequencing data are analyzed using bioinformatics pipelines for taxonomic classification and diversity analysis.

Clinical assessments include validated acne severity grading systems, inflammatory and non-inflammatory lesion counts, and evaluation of treatment response during follow-up. Healthy volunteers provide baseline microbiome samples for comparison with acne participants before treatment.

The primary objective is to characterize longitudinal changes in the facial skin microbiome during isotretinoin treatment in patients with moderate-to-severe acne vulgaris. Secondary objectives include comparing baseline microbiome characteristics between acne patients and healthy individuals and exploring associations between microbiome composition and clinical treatment outcomes.

Study findings may contribute to a better understanding of microbiome dynamics during isotretinoin therapy and provide a foundation for future microbiome-targeted approaches in acne management.

Inclusion criteria

Acne Vulgaris Cohort:

• Participants aged 12-35 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.