In vitro and in vivo antimicrobial activity of water-soluble chitosan oligosaccharides against Vibrio vulnificus.

Vibrio vulnificus is a Gram-negative bacterium that induces severely rapid pathological progress. In this study, we evaluated the antibacterial activity of two water-soluble chitosan oligosaccharides, COS A (MW, 10,000 Da) and COS B (MW, 1,000 Da), from 90-95% deacetylated chitosan, against V. vulnificus in vitro and in vivo. Treatment with COS A resulted in significantly higher suppressive effects on the growth of V. vulnificus than treatment with COS B. The growth of V. vulnificus was inhibited within 1 h of treatment with water-soluble COS A in concentrations ranging from 0.5 to 10 mg/ml. Additionally, treatment with COS A completely inhibited V. vulnificus-induced cytotoxicity in human intestinal epithelial INT-407 cells, while COS B did not. Furthermore, the administration of COS A (0.1-0.5 mg per mouse) significantly increased the survival period of V. vulnificus-infected mice. The number of viable V. vulnificus in the spleen, liver, small intestine, and blood was significantly lower in COS A-treated mice than in untreated mice. Here, we clearly demonstrate that COS A is a potential agent for the prevention and treatment of infection with V. vulnificus.