An Assessment of Debridement Tools to Disrupt Biofilms and the Ability of an Autolytic Debridement Dressing to Minimise Spreading of Bacteria Across the Wound Sellars L E, Rippon M G and Westgate S J.
Introduction Debridement tools allow healthcare practitioners to carry out mechanical debridement. Although this method may be efficient at disrupting wound biofilms there is potential for bacteria to be transferred around the wound bed by mechanical debridement tools. Autolytic debridement dressings that promote the body’s natural process of enzymatic debridement aim to reduce necrotic tissue and biofilm material without the risk of spreading bacteria across the wound.
Aim To compare a mechanical debridement tool with an autolytic debridement wound dressing, and assess whether the debridement products transfer bacteria between surfaces, following disruption of a bacterial biofilm.
Results
• Ex-vivo porcine skin explants were inoculated with a bacterial suspension of P. aeruginosa and incubated at 37°C for 4 hours to encourage bacterial growth. • Explants were washed 3 times with PBS to mimic wound irrigation prior to debridement. • Pre-formed biofilms were covered with HydroClean® plus and incubated for 24 hours at 37°C or mechanically debrided with Product D. • Following treatment debridement samples were transferred to three sterile porcine skin explants. • Viable microorganisms were recovered from all 3 porcine explants in order to quantify bacteria recovered from inoculated and initially sterile porcine explants. • HydroClean® plus Dressings and debridement tools were also imaged post inoculation using scanning electron microscopy.
• Samples of HydroClean® plus, used to treat P. aeruginosa biofilms, resulted in less visual bacterial transfer after 24 hours than Product D (Figure 1). • HydroClean® plus significantly reduced the quantity of P. aeruginosa transferred from the initial inoculated explant to subsequent explants (Figure 2). • The quantity of bacteria transferred from treated explants to sterile explants remained >6.83 log when the mechanical debridement tool, Product D was used (Figure 2). • Following exposure to P. aeruginosa inoculum individual bacterial colonies were present on the fibres of the inner core of HydroClean® plus. Bacterial colonies covered a significant proportion of the fibres of the mechanical debridement tool (Figure 3).
Discussion & Conclusions
A
B
C
Figure 1. TSA plates exposed to A = Negative control, B = HydroClean® plus or C = Product D, after 24 hours incubation with porcine explants, inoculated with 100 µl 1 x 103 cfuml-1 Pseudomonas aeruginosa and incubated for 4 hours at 37°C.
Log10cfuml-1
Method
10 9 8 7 6 5 4 3 2 1 0
Average Initial Sample First Transfer Third Transfer
Negative control
Hydroclean plus
Product D
Product
Figure 2. Quantity of viable Pseudomonas aeruginosa recovered from inoculated porcine explants treated with a debridement product (Initial Sample) and quantity transferred to fresh porcine explants.
Figure 3. Scanning electron micrographs of HydroClean® plus (A) and Product D (B) after 24 hours exposure to a Pseudomonas aeruginosa inoculum (Purple = Pseudomonas aeruginosa).
Product D resulted in the transfer of P. aeruginosa from an inoculated porcine explant to un-inoculated explants. Treatment with HydroClean® plus significantly reduced this transfer. The risk of recontamination of the wound bed was reduced when autolytic debridement was used in place of mechanical debridement. SEM evidence suggested that the autolytic debridement dressing sequestered and retained the bacteria within the dressing core. This project was carried out by Perfectus Biomed Ltd. and funded by Paul Hartmann Limited Perfectus Biomed is an independent testing laboratory. SciTech Daresbury, Keckwick Lane, Cheshire, WA4 4AD Tel +441925 864 838 Mob: +447841 342 904, E-mail
[email protected] Product D - Debrisoft® Debridement Pad