Antimicrobial Properties of a Chitosan Dextran-Based Hydrogel for Surgical Use

Abstract

ABSTRACTA chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activityin vitroagainst a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species. Scanning and transmission electron microscopy were carried out to elucidate the antimicrobial mechanism of this compound. CD hydrogel was found to be effective againstStaphylococcus aureus,Streptococcus pyogenes,Escherichia coli, andClostridium perfringensat its surgical concentration of 50,000 mg/liter. Minimum bactericidal concentrations ranged from 2,000 to 50,000 mg/liter. Dextran aldehyde (DA) was found to be the antimicrobial component of the CD hydrogel with MBC ranging from 2,000 to 32,000 mg/liter.S. aureusappeared to be killed at a slightly faster rate thanE. coli. Candida albicansandPseudomonas aeruginosawere more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy ofE. coliandS. aureusincubated with CD hydrogel and DA alone revealed morphological damage, disrupted cell walls, and loss of cytosolic contents, compatible with the proposed mode of action involving binding to cell wall proteins and disruption of peptide bonds. Motility and chemotaxis tests showedE. colito be inhibited when incubated with DA. The antibacterial activity of CD hydrogel may make it a useful postsurgical aid at other body sites, especially where there is a risk of Gram-positive infections.