Chitosan is a natural biopolymer produced by the deacetylation of chitin, a component of shells (exoskeleton) of crustaceans such as crabs, shrimps and lobsters. It has important functional activities but its poor solubility limits its food and medicinal applications.
Chitosan oligosaccharides (COS), also called oligochitosans, are produced by the enzymatic hydrolysis of chitosan and have a good solubility in water, making them more usable. A new study evaluated its antibacterial action and its possibility of being used in the treatment of acne vulgaris for its action against Propionibacterium acnes. Oligochitosan showed a potent antibacterial effect on P. acnes. In particular, 10 kDa oligochitosan presented the highest antimicrobial effect with values ​​of minimum inhibitory concentration of 32-64 μg / mL. Furthermore, oligochitosan in combination with tetracycline and erythromycin enhanced their antibacterial effect on P. acnes

Kim, Song-Hee, et al. “Oligochitosan as a potential anti-acne vulgaris agent: combined antibacterial effects against Propionibacterium acnes.” Food Science and Biotechnology 26.4 (2017): 1029-1036.