Antimicrobial properties of a chitosan dextran-based hydrogel for surgical use.
A chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activity in vitro against 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 against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Clostridium perfringens at 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. aureus appeared to be killed at a slightly faster rate than E. coli. Candida albicans and Pseudomonas aeruginosa were more resistant to CD hydrogel and DA. Scanning and transmission electron microscopy of E. coli and S. aureus incubated 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 showed E. coli to 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.
Department of Chemistry, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
Manal A
MA
Aziz
Jaydee D
JD
Cabral
Heather J L
HJ
Brooks
Stephen C
SC
Moratti
Lyall R
LR
Hanton
D000447:Aldehydes / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development; D002177:Candidiasis / Q000188:drug therapy / Q000382:microbiology; D002473:Cell Wall / Q000187:drug effects* / Q000648:ultrastructure; D048271:Chitosan / Q000737:chemistry / Q000494:pharmacology*; D003911:Dextrans / Q000737:chemistry / Q000494:pharmacology*; D004724:Endoscopy; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development
D000447:Aldehydes; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D003911:Dextrans; D008565:Membrane Proteins; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D048271:Chitosan