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Wound healing is compromised by critical colonization and infection with bacteria. Hence, antimicrobial agents are used clinically to decrease the bacterial load and promote wound healing. Polihexanide (PHMB) has been found to be effective against a broad spectrum of micro-organisms and is increasingly utilized in rinsing solutions or in combination with wound dressings because of its good biocompatibility. In the present study, a co-culture of human keratinocytes and Staphylococcus aureus was established to serve as an in vitro model for infected wounds. Incubation of keratinocytes with increasing concentrations of S. aureus led to a dose-dependent decline of cell viability and proliferation. Lactate dehydrogenase release and interleukin-8 liberation were found to be elevated under these conditions. Polihexanide dose-dependently was able to protect keratinocytes from bacterial damage and re-establish normal human cell proliferation in vitro. Furthermore, a dressing consisting of biocellulose derived from Acetobacter xylinum with the addition of polihexanide was adept to safeguard keratinocytes against S. aureus. In conclusion, the co-culture system presented embodies a valuable tool as a model system for infected cells in a non-healing wound. Furthermore, the results obtained support the favorable function of polihexanide in the treatment of infected chronic wounds.

Infection may lead to the formation of a chronic wound or is a common complication during their treatment. Rather than relying on just debriding and cleansing the wound, additional therapeutic strategies are commonly applied in an attempt to prevent infection. Therefore, wound dressings combined with antimicrobial agents such as silver, povidine iodine, or polihexanide are increasingly utilized in the treatment of critical colonized or infected chronic wounds. Polihexanide is regarded first choice as therapy option because of its good skin tolerance beside its antimicrobial effects. Furthermore, a positive influence of polihexanide on wound closure was observed in a study with aseptic wounds in piglets. Moreover, polihexanide is able to induce cell proliferation in vitro. In vitro test systems provide valuable tools in the study of substance or material effects on cells. They use highly defined culture conditions and avoid the complex mechanisms which occur in vivo and thus allow the direct measurement of the influence on cell viability and proliferation. For instance, the anti-oxidative effect can be determined and the antimicrobial activity measured in vitro. Furthermore, a co-culture system of HaCaT keratinocytes and Staphylococcus aureus was used to test the capacity of polihexanide to protect the cells from the bacterial damage. Although antiseptics have a lower potency to induce bacterial resistance than antibiotics, concerns have been expressed regarding the overuse of antiseptics and the possible emergence of bacterial adaptation. Hence, an experimental system using microplatelaser-nephelometry was employed to test the adaptation capacity of Staphylococcus aureus during repeated treatment with polihexanide.

In the treatment of chronic wounds, it is necessary to establish a physiological wound milieu to improve healing. Application of collagen as wound dressing has been described as beneficial as it possesses the ability to reduce elevated levels of proteases, cytokines, and free radicals. Consequently, a wide range of wound dressings based on collagen have been developed. Native collagen is susceptible to alterations because of influences during the production process; to minimize effects on the molecule itself collagen wound dressings are usually aseptically produced. Common sterilization methods (autoclaving, irradiation, and ethylene oxide (EtO) treatment) can induce changes in the protein chemistry and physical properties, potentially affecting the absorption rate, mechanical strength, or performance. In this study, we have evaluated the influence of gamma- and beta-irradiation as well as EtO sterilization on the binding capacity of collagen type I for selected proteases and cytokines associated with nonhealing wounds. Although a pronounced effect on the physical properties of the collagen was found, there was no significant loss in the binding affinity for polymorphonuclear elastase, matrix metalloproteinase-2, and interleukin-1beta, or in the antioxidant capacity.

Exudate can be an excellent indicator of what is happening within a wound and, therefore, provides valuable information during patient assessment. The volume, consistency, and particularly odour and colour, of any exudate will inform the practitioner about bacterial contamination, infection and stage of healing (Hampton and Collins, 2003). However, in the chronic wound, exudate must be effectively managed if the optimal moist environment necessary for wound healing is to be created, the negative effects of chronic exudate on fibroblasts are to be avoided (Phillips et al, 1998), and the surrounding skin protected from the risks of maceration (White, 2006). It is, therefore, important to understand chronic exudate and its effects so that appropriate treatment for the wound and peri-wound area is provided. Flivasorb® (Activa Healthcare) dressings, which include superabsorber particles, can absorb the exudate and retain it firmly within the dressing, ensuring that the potentially damaging chronic wound exudate does not reflect back onto the wound, causing maceration. This article will describe the role of exudates in wound healing, the problems associated with chronic wound exudates and how Flivasorb dressings with superabsorbent particles can provide an optimum healing environment in highly exuding wounds.