COMBATING WOUND-RELATED BIOFILMS

Mia Mae Kiamco

This research aimed to develop treatment combination and techniques to combat wound-related biofilms such as Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa. Hyperosmotic agents were combined with antibiotics to improve the latter’s efficacy; cell viability, biofilm morphology, oxygen penetration, and biofilm metabolism were investigated. Biofilms were grown in flow cells to image and analyze the structure of biofilms using Confocal Laser Scanning Microscope. Dissolved oxygen (DO) microelectrodes were constructed and used to measure oxygen depth profiles in biofilms. Volumetric biofilm coverage in wound-related biofilm was reduced under combined treatments of maltodextrin and vancomycin. DO profiles showed that the combination treatment against wound-related biofilms increased the DO concentration near the bottom of the biofilm. The presence of oxygen is needed for wound healing to occur. Moreover, similar results were achieved when medical-grade honey and cadexomer iodine were used in combination with antibiotics; combining cadexomer iodine and ciprofloxacin improved DO concentration and penetration depth into the biofilm, while medical-grade honey was associated with low pH, a desirable environment for wound healing. Nuclear magnetic resonance spectroscopy was used to study the metabolic activity of biofilms after combination treatment of maltodextrin and vancomycin. The presence of metabolites (products of the fermentation process) and oxygen levels below the detection limit in biofilms treated with vancomycin-only indicated that cells within the biofilm are respiring through fermentation under anaerobic conditions. Conversely, combining maltodextrin with vancomycin showed a lower concentration of fermentation byproducts and higher oxygen concentration near the bottom of the biofilms. Finally, this dissertation tackles the development of a novel antibiotic-free electrochemically-active wound dressing that produces a low concentration of antiseptics (hypochlorous acid or HOCl) to eradicate wound-related biofilms without damaging host tissues. The electrochemical-scaffold was constructed as a 3-electrode system with the working and counter electrodes made of carbon fabric and the reference electrode made of silver/silver chloride. HOCl e-scaffold eradicated in vitro biofilms within 3 hours of exposure. Moreover, HOCl e-scaffold significantly reduced ex vivo biofilms on porcine dermal explants without causing any harm to the host tissue. Overall, this dissertation presents a multi-approach treatment and an antibiotic-free strategy to combat wound-related biofilms.

COMBATING WOUND-RELATED BIOFILMS

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