(LR-023) The Antibiofilm Efficacy and Depth Penetration of Prototype Wound Dressings Using Wounded Ex Vivo Human Skin

Isabel Laubach, BS – Scientist, Perfectus Biomed Group; Marnie Peterson, PhD, PharmD – Site Director, Perfectus Biomed Group; Nora Bastida Agote, BS – Hartmann Group; Markus Kettel, PhD – Hartmann Group

Introduction: Biofilms are the leading cause in the stalling of wound healing in clinical settings as they can penetrate deep into tissue and evade topical antimicrobial treatment. Ex vivo human skin models allow for moderately high throughput screening while remaining clinically relevant by using a host-derived substrate, allowing for multiple experimental outputs and data types. This study aimed to determine the biofilm disruption and antibiofilm depth penetration properties of two new prototype wound dressings, using a wounded skin model.

Methods: Intact human skin tissue explants (5 mm) were produced with 2 mm partial thickness wounds. Explant wound beds were inoculated with Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus (Xen30) and incubated to establish 48 or 72 hour biofilms. Wounds beds were washed to remove planktonic bacteria and treated with liquid active (100 μL/treatment), commercially available non-border superabsorbent dressings (Dressing 1)*, commercially available non-medicated impregnated wound contact layers (Dressing 2)^#, or respective new prototype dressings (Prototype Dressing 1 or Prototype Dressing 2). After 24 hours of treatment, explants were sonicated, vortexed, and released bacteria plated for enumeration. Biofilm viability was assessed by Live/Dead staining of one explant replicate and imaged. Two explants from each treatment were reserved for histology with hematoxylin and eosin (H&E) and Gram-Twort staining.

Results: Of the dressings tested, the new Prototype Dressing 1 demonstrated the greatest overall log reduction for both organisms, 3.56 log₁₀ reduction from 72 hour P. aeruginosa controls and 0.98 log₁₀ reduction from 96 hour MRSA controls. Greater efficacy for Prototype Dressing 1 compared to legacy Dressing 1* was supported by log10 CFU/explant recovered post treatment as well as less remaining biofilm in wound beds of tissue explants as observed by histology. Prototype Dressing 2 was likewise more effective than legacy impregnated Dressing 2^#. Both prototype dressings were outperformed by only the liquid active.

Organism	Log Reduction from Growth Control(Mean±SD)
	Liquid Active	Dressing 1*	Prototype Dressing 1	Dressing 2#	Prototype Dressing 2
P. aeruginosa	>3.35±0.30	0.36±0.05	3.56±0.42	0.39±0.08	1.46±0.07
MRSA	>2.98±0.96	0.67±0.02	0.98±0.25	0.30±0.02	0.62±0.08

Discussion: This study determined newly designed prototype dressings demonstrated greater antibiofilm efficacy than their existing commercial predicates. Histology showed that the bacteria, although killed, remained in the wound bed when treated with liquid active alone as compared to any of the physical dressings assessed. The possibility exists that the physical wound dressings, along with the antibiofilm efficacy, may function to physically remove bacteria from the wound bed when discarded post treatment.

Trademarked Items: * Zetuvit Plus, Hartmann, 2023
# Atrauman , Hartmann, 2023

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