Rhamnolipids and Essential Oils: A New Approach to Managing Bacteria Associated with Skin Diseases

The rise of antimicrobial-resistant pathogens has increased interest in biologically derived compounds for treating dermal infections. This study evaluates the effect of rhamnolipid, a biosurfactant produced by Pseudomonas aeruginosa, in combination with essential oils of oregano (Origanum vulgare), tea tree (Melaleuca alternifolia), and cinnamon (Cinnamomum cassia) against Cutibacterium acnes and Staphylococcus aureus, with or without incorporation into a sodium alginate-based film. Minimum bactericidal concentrations (MBC), biofilm inhibition development, and time-kill assays were used to assess antimicrobial activity. Results indicate MBCs of 800 mg/L for rhamnolipid, 0.05% for oregano, 0.2% for tea tree oil, and 0.5% for cinnamon against C. acnes. For S. aureus, the MBCs are 2500 mg/L, 0.07%, 0.3%, and 0.5%, respectively. When combined the rhamnolipids and the essential oils, the MBC for C. acnes were reduced to 500 mg/L of rhamnolipid and essential oils of oregano, tea tree and cinnamon were reduced to 0.03%, 0.1% and 0.3%, respectively, and for S. aureus were reduced to 1500 mg/L of rhamnolipid and essential oils of oregano, tea tree and cinnamon were reduced to 0.05%, 01% and 0.3%, respectively. A sodium alginate-based polymer film was formulated with rhamnolipid, maintaining antimicrobial efficacy and water-retention capacity but with reduced mechanical strength. These findings suggest a promising topical application for treating dermal infections.