Biofilm Disruption Activity of Multi-Action Wound Treatment

Introduction: The aim of this study was to assess the biofilm disruption activity of a novel multi-action treatment (MAT*) and a carboxymethylcellulose (CMC) gelling-fibre silver dressing with added surfactants (CGSD) in two in-vitro models providing increasing challenge to the treatment. MAT treatment comprises a formulation including povidone iodine in a CMC gelling fibre format.

Methods:

Method 1: CDC reactor biofilm model. Method was as previously reported1 with the following exceptions: Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans were used to develop a mixed-species biofilm on polycarbonate coupons. Glass coupons were also utilised, stained with FilmTracerTM viability stain and imaged using a confocal microscope.

Method 2: Colony Drip Flow Reactor® (CDFR) model. Three, single species biofilms were developed over 24 hours on a multi-layer surface. The method was based on the methodology outlined in Lipp et al 20102. Dressings were activated by introducing phosphate buffered saline plus 1% of appropriate broth to 80% of absorbent capacity.

Results: Method 1: Following treatment with MAT or CGS no viable organisms were recovered from CDC reactor biofilms. This was a reduction of 7.12±0.00 Log10CFUmL-1 compared to negative control. Confocal images of coupons treated with CGSD showed a small quantity of red (dead) cells. Images of coupons treated with MAT showed no cells, alive or dead, suggesting a biofilm removal effect. Method 2: Following treatment with MAT no viable organisms were recovered from CDFR biofilms. Log reductions as follows, for MAT, then CGSD: Pseudomonas aeruginosa: 8.01±0.00 & 1.36±0.54 Log10CFUmL-1; Staphylococcus aureus: 10.27±0.00 & 4.99±1.14 Log10CFUmL-1; Candida albicans: 4.18±0.00 & 3.33±0.60 Log10CFUmL-1.

Discussion: It was previously shown that the highly absorbent MAT was effective in disrupting single-species biofilms in the CDC model1. This study demonstrated the same ability in a more challenging multi-species model and a colony drip-flow model that more closely replicates the biofilms observed in chronic wounds. MAT was more effective than CGSD in the more representative colony drip-flow model. Based on the effect demonstrated during these studies we plan to investigate the performance in skin-equivalent models and ultimately in human use.