Oligochitosan as a potential anti-acne vulgaris agent: combined antibacterial effects against Propionibacterium acnes.

To develop an antibacterial treatment for acne vulgaris using natural substance with few side effects, we investigated the antibacterial activities of oligochitosan against acne-related bacteria, particularly Propionibacterium acnes. Oligochitosan showed potent antibacterial effect on P. acnes. Especially, 10 kDa oligochitosan presented the highest antimicrobial effect with minimum inhibitory concentration values of 32-64 µg/mL on P. acnes. In addition, oligochitosan clearly reversed the antibacterial effect of tetracycline and erythromycin on P. acnes in the combination mode. The combination of tetracycline- or erythromycine-10 kDa oligochitosan resulted in a median ΣFIC range of 0.02-0.56, suggesting that the antibiotics-oligochitosan combination resulted in an antibacterial synergy against P. acnes. Thus, the results obtained in this research strongly supported that erythromycin and tetracycline will restore the antibacterial activity against P. acnes in the combination mode with 10 kDa oligochitosan.