Anti-biofilm efficacy of a lactoferrin/xylitol wound hydrogel used in combination with silver wound dressings

Abstract

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 Acticoat™ 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.

Figure 1

Images of a colony‐drip‐flow reactor. Established biofilms are treated with 0·5 ml hydrogel (lanes 2 and 3) prior to application of wound dressing (lanes 4–6).

Figure 2

Log reductions (LRs) for Pseudomonas aeruginosa biofilms treated without or with silver‐based wound dressings and with commercial hydrogel or lactoferrin/xylitol hydrogel. LRs for wound dressing alone are also shown. Combined hydrogel and wound dressing treatments assayed viability for biofilms treated with Tegaderm™ Ag, Aquacel® Ag and Acticoat™. All LRs are normalised to the gauze control. Data are presented as mean ± standard error. Asterisk denotes statistically significant difference between hydrogel samples.

Figure 3

Log reduction (LR) in viability of dual species biofilms treated with either commercial hydrogel or lactoferrin/xylitol hydrogel in combination with either gauze dressing or Acticoat™. LRs for dressings alone are also shown. Data are presented as average ± standard deviation. Asterisk denotes statistically significant difference between hydrogel samples (P≤ 0·05).