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The treatment of chronic wounds presents a major challenge in medical care. In particular, the effective treatment of bacterial infections that occur in the form of biofilms is of crucial importance. To develop successful antibiofilm strategies for chronic wound treatment, biofilm models are needed that resemble the in vivo situation, are easy to handle, standardizable, and where results are readily transferable to the clinical situation. We established two 3D biofilm models to distinguish the effectiveness of wound dressings on important microorganisms present in chronic wounds. The first 3D biofilm model contains Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii, while the second is based on Pseudomonas aeruginosa. Bacteria are cultivated in a nutrient-rich agar/gelatin mix, into which air bubbles are incorporated. This results in a mature biofilm growing in clusters similar to its organization in chronic wounds. The models are convenient to use, have low variability and are easy to establish in the laboratory. Treatment with polihexanide and silver-containing wound dressings showed that the models are very well suited for antimicrobial testing and that they can detect differences in the efficacy of antimicrobial substances. Therefore, these models present valuable tools in the development of effective antibiofilm strategies in chronic wounds.

Antibacterial activity of dressings containing antimicrobials is mostly evaluated using in vitro tests. However, the various methods available differ significantly in their properties and results obtained are influenced by the method selected, micro-organisms used, and extraction method, the degree of solubility or the diffusability of the test-compounds. Here, results on antimicrobial activity of silver-containing dressings obtained by agar diffusion test (ADT), challenge tests (JIS L 1902, AATCC 100), and extraction-based methods (microplate laser nephelometry (MLN), luminescent quantification of bacterial ATP (LQbATP)) using Staphylococcus aureus and Pseudomonas aeruginosa were evaluated. Furthermore, the effect of the pH on antibacterial efficacy of these dressings was investigated. All silver-containing dressings exerted antimicrobial activity in all in vitro tests and results correlated considerably well. Differences were observed testing the agent-free basic materials. They did not exhibit any antimicrobial effects in the ADT, MLN or LQbATP, since these methods depend on diffusion/extraction of an active agent. However, they showed a strong antimicrobial effect in the challenge tests as they possess a high absorptive capacity, and are able to bind and sequester micro-organisms present. Therefore, it seems recommendable to choose several tests to distinguish whether a material conveys an active effect or a passive mechanism. In addition, it could be shown that release of silver and its antimicrobial efficacy is partially pH-dependent, and that dressings themselves affect the pH. It can further be speculated that dressings' effects on pH and release of silver ions act synergistically for antimicrobial efficacy.

Introduction:

Efficacy of a adebridement product and a bcollagen dressing on inflammation reduction and re-starting healing was evaluated in ten frail elderly patients with stagnating skin lacerations, treated in a nursing home setting. Skin tears often occur in these patients, due to their poor condition and their medication such as corticosteroids and anti-coagulants.

Methods:

Case ascertainment was used. Patients received a bcollagen dressing and a cfoam or an dalginate as a secondary dressing, for a maximum of 14 days, after which the bcollagen dressing was discontinued and the cfoam used as a primary dressing. A tubular compressione system was used to reduce oedema that was present

in the leg. Wound healing was assessed using clinical observation and digital photographs, comparing day 0 versus day 14 results. Patients were then followed up until wound closure.

Results:

Eight women and two men were included and completed the study period. Patients had a mean age of 76 years (ranging from 62-100 years). All included wounds had closed within 12 weeks of treatment. Two typical cases are included to demonstrate the results.

Conclusion:

The results indicate that the use of the bcollagen dressing stimulated wound healing in these stagnating wounds. Moreover the bcollagen dressing has effectively stopped the bleeding.

Introduction:

Wound dressings with antimicrobial agents are increasingly utilized in the management of critical colonized or infected chronic wounds. The dressings’ antibacterial activities are mostly evaluated using in-vitro-tests. These may differ significantly in their properties and outcome. We have analyzed the antibacterial effect of PHMB- and silver-dressings using in-vitro-methods such as the agar diffusion test (ADT), contact tests like JISL1902:2002 or AATCC100, microplate-laser nephelometry (MLN) and luminometric quantification of bacterial ATP (LQb).

Materials & Methods:

Antibacterial activity of the dressings was tested against Staphylococcus aureus and Pseudomonas aeruginosa. ADT was performed according to DIN58940-3 with samples of 0.6 cm2. For AATCC100 samples sizes of 18 cm2 and for JISL1902:2002 of 400 mg were used. Dressing extracts were prepared corresponding to DIN10993-12 for MLN and LQb.

Results:

PHMB- and silver-dressings showed antibacterial activity in all tests. Yet, total effectiveness varied for single methods and properties of the basic dressing materials without active agent (such as alginate, cellulose, or polyurethane). Alginate, cellulose, or polyurethane alone had no effect in ADT. In contrast, alginate showed a strong antibacterial activity in the contact tests (JISL1902:2002, AATCC100) because it is able to sequester bacteria during gel formation. MLN and LQb only determined a bactericidal effect on S. aureus and P. aeruginosa for the agent-containing dressings.

Conclusions:

Using in-vitro-tests for the evaluation of the antibacterial activity allows quantification and direct comparison of dressings’ effectiveness under standard conditions. Various test methods are available that differ in their properties and hence in their outcome, this has to be taken into account when selecting a specific test and interpreting the results.

BACKGROUND

In Hong Kong, at the time of the study, compression treatment was not considered usual care for venous leg ulcer patients.

AIM

This randomized controlled trial compared quality of life (QOL) aspects in venous leg ulcer patients of over 55-years of age, of short-stretch compression (SSB), four-layer compression bandaging (4LB) and usual care (UC) (moist wound healing dressing, no compression).

METHOD

Study period was 24-weeks, the primary outcome was the patient functional status, disease-specific and generic health-related QOL measures and ulcer healing rates, comparing week 1 vs. week 24 (end) results. Assessments included photogrammetry, Brief Pain Inventory, SF-12 Health Survey, Charing Cross Venous Ulcer Questionnaire and Frenchay Activity Index. Data analysis was performed using, where appropriate; Kaplan Meier and log rank chi-square and the repeated measures analysis of variance test.

RESULTS

A total of 321 patients participated in the study, 45 (14%) withdrew for various reasons. Compression bandaging in both groups significantly reduced pain (P < 0.0001) and improved functional status and QOL. Healing rate at 24 weeks for both compression groups was significant (P < 0.001); for SSB this was 72.0% (77/107) vs. 67.3% in the 4LB group (72/107) and 29.0% (31/107) with usual care. The reduction in ulcer area from weeks 12 to 24 was significant only for SSB (P < 0.047).

CONCLUSION

Compression was shown to be feasible for elderly community care patients in Hong Kong and is currently implemented as part of standard venous leg ulcer treatment.