Browsing by Author "Ward, L. S."

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Anti-biofilm efficacy of a lactoferrin/xylitol wound hydrogel used in combination with silver wound dressings
(2011-04) Ammons, Mary Cloud B.; Ward, L. S.; James, Garth A.
With an epidemic increase in obesity combined with an ageing population, chronic wounds such as diabetic foot ulcers, pressure ulcers and venous leg ulcers are an increasing clinical concern. Recent studies have shown that bacterial biofilms are a major contributor to wound bioburden and interfere with the normal wound healing process; therefore, rational design of wound therapies should include analysis of anti-biofilm characteristics. Studies using the combined treatment of bacterial biofilms with the innate immune molecule lactoferrin and the rare sugar-alcohol xylitol have demonstrated an antimicrobial capacity against a clinical wound isolate.Studies presented here used a colony-drip-flow reactor biofilm model to assess the anti-biofilm efficacy of a lactoferrin/xylitol hydrogel used in combination with commercially available silver-based wound dressings. Log reductions in biofilm viability are compared with a commercially available wound hydrogel used in combination with the silver-based wound dressings. For both a single species biofilm and a dual species biofilm, the lactoferrin/xylitol hydrogel in combination with the silver wound dressing Acticoatâ„¢ had a statistically significant reduction in biofilm viability relative to the commercially available wound hydrogel. This study also demonstrated a statistical interaction between the lactoferrin/xylitol hydrogel and the silver wound dressing.
Combined treatment of Pseudomonas aeruginosa biofilm with lactoferrin and xylitol inhibits the ability of bacteria to respond to damage resulting from lactoferrin iron chelation
(2011-04) Ammons, Mary Cloud B.; Ward, L. S.; Dowd, Scot E.; James, Garth A.
With an ageing and ever more obese population, chronic wounds such as diabetic ulcers, pressure ulcers and venous leg ulcers are an increasingly relevant medical concern. Identification of bacterial biofilm contamination as a major contributor to non-healing wounds demands biofilm-targeted strategies to manage chronic wounds. Pseudomonas aeruginosa has been identified as a principal biofilm-forming opportunistic pathogen in chronic wounds. The innate immune molecule lactoferrin and the rare sugar alcohol xylitol have been demonstrated to be co-operatively efficacious against P. aeruginosa biofilms in vitro. Data presented here propose a model for the molecular mechanism behind this co-operative antimicrobial effect. Lactoferrin iron chelation was identified as the primary means by which lactoferrin destabilises the bacterial membrane. By microarray analysis, 183 differentially expressed genes of ≥1.5-fold difference were detected. Interestingly, differentially expressed transcripts included the operon encoding components of the pyochelin biosynthesis pathway. Furthermore, siderophore detection verified that xylitol is the component of this novel synergistic treatment that inhibits the ability of the bacteria to produce siderophores under conditions of iron restriction. The findings presented here demonstrate that whilst lactoferrin treatment of P. aeruginosa biofilms results in destabilisation of the bacterial cell membrane though iron chelation, combined treatment with lactoferrin and xylitol inhibits the ability of P. aeruginosa biofilms to respond to environmental iron restriction.
In vitro susceptibility of established biofilms composed of a clinical wound isolate of Pseudomonas aeruginosa treated with lactoferrin and xylitol
(2009-03) Ammons, Mary Cloud B.; Ward, L. S.; Fisher, Steve T.; Wolcott, Randall D.; James, Garth A.
The medical impact of bacterial biofilms has increased with the recognition of biofilms as a major contributor to chronic wounds such as diabetic foot ulcers, venous leg ulcers and pressure ulcers. Traditional methods of treatment have proven ineffective, therefore this article presents in vitro evidence to support the use of novel antimicrobials in the treatment of Pseudomonas aeruginosa biofilm. An in vitro biofilm model with a clinical isolate of P. aeruginosa was subjected to treatment with either lactoferrin or xylitol alone or in combination. Combined lactoferrin and xylitol treatment disrupted the structure of the P. aeruginosa biofilm and resulted in a >2log reduction in viability. In situ analysis indicated that while xylitol treatment appeared to disrupt the biofilm structure, lactoferrin treatment resulted in a greater than two-fold increase in the number of permeabilised bacterial cells. The findings presented here indicated that combined treatment with lactoferrin and xylitol significantly decreases the viability of established P. aeruginosa biofilms in vitro and that the antimicrobial mechanism of this treatment includes both biofilm structural disruption and permeablisation of bacterial membranes.