Testing wound dressings using an in vitro wound model

Abstract

Objective-To determine whether or not there are any significant differences in the effects of wound dressings on bacterial bioburden.Method-A selection of non-occlusive, non-adhesive dressings was tested for their effect on bacterial bioburden. The dressings selected included two dressings with antimicrobial properties (one containing silver and one containing PHMB), a cotton-based dressing enclosed in a perforated sleeve of poly(ethylene terephthalate), a carboxymethyl cellulose-based dressing, a fibre-free alginate dressing, and a 12-ply 100% cotton gauze. Using the colony-drip flow reactor (DFR) model, a meticillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa biofilm was grown underneath a dressing sample. Biofilm growth was examined via plate counts, fluorescent microscopy and scanning electron microscopy.Results-The dressings containing antimicrobial agents had the greatest effect on bacterial load. In the MRSA experiments, both antimicrobial dressings produced lower bacteria counts than the other dressings (p≤0.001), while in the P. aeruginosa experiments, only the silver-containing sample had fewer bacteria (p≤0.0001). However, neither antimicrobial dressing was able to completely eradicate the bacteria when testing with either microorganism. Conclusion-The results presented herein illustrate that bacteria can grow unchallenged within the dressing environment and that an antimicrobial dressing can limit this bacterial growth. Keywordsantimicrobial dressings; biofilms; plate counts; fluorescent microscopy; scanning electron microscopy Wounds are an ideal environment for bacterial colonisation and biofilm formation. The wound bed provides both a surface on which to grow and an ample supply of nutrients. Recent studies have shown that bacteria inoculated into wounds form biofilms. 1,2 Another study found that as many as 60% of chronic wound specimens contained a biofilm. 3 Current research indicates that biofilms are present in chronic wounds. [3][4][5][6] Furthermore, recent studies suggest that biofilms should be targeted when developing and testing therapies for these wounds. [7][8][9][10][11] A literature review of culture data from 62 published studies dating from 1969 to 1997 revealed that the predominant wound isolate in both chronic and acute wounds was Staphylococcus aureus (reported in 63% of the studies), followed by coliforms (45%), Bacteroides spp. (39%), Peptostreptococcus spp. (36%), Pseudomonas aeruginosa (29%), Enterococcus spp. (26%) and Streptococcus pyogenes (13%).

Comparative study of the antibacterial penetrating effects of wound dressings

“…Nonetheless, clinicians are often confused on selecting from a large variety of wound dressings. Then, many comparative studies on the antibacterial effects of wound dressings have been conducted 11 - 15. However, the antibacterial effects of wound dressings have not been investigated using the LB liquid medium in the in vitro model with E coli in detail.…”

Evaluation of Mouse Wound Models for Probiotics-Based Wound Infection Prevention Study

“…These wound models consisted of (1) simple full thickness skin incision, (2) stitched skin flap, (3) burn (with liquid nitrogen), and (4) skin incision with circulatory disruption [2,4,8,9].…”

“…The model should be low cost, yet closely approximate the early wound as it may be experienced by the warfighter. To this end, the objective of this study was to evaluate the ability of probiotics to limit and/or reduce bacterial infection in different models of wounds, from simple dermal wounds to more complex wounds [4][5][6][7].…”

Anti-Biofilm Drug Susceptibility Testing Methods: Looking for New Strategies against Resistance Mechanism

“…Biofilm is related with failures in epithelialization and granulation tissue formation, and promotes a low-grade inflammatory response that interferes with wound healing, so that is important develop techniques that evaluate antibiofilm wound management [86]. The colony-drip flow reactor (DFR) was implemented for to evaluate in vitro biofilms in a way that simulates the chronic wound environment [87,88]. Equally, constant depth film fermenter (CDFF) has been used in the formation of multiple biofilms from wounds.…”