Irrigation of chronic wounds with tap water as a prerequisite for improved healing

Dear Editors, We would like to congratulate Dr Tzong-Shiun Li and co-authors regarding their letter to the editor (1). We agree with their statement of treating bacterial contaminated wounds by frequent irrigation with tap water. This simple alternative to expensive pharmaceutical products is not only much more cost-effective, but might also be superior in its outcome. The effect of bacterial biofilms as the cause of persistent infections with poor wound healing is known (2). Biofilms may contain heterogeneous colonies of bacteria, fungi or protozoa. The matrix of this polymicrobial complex consists of water, polysaccharides, proteins and lipids. Biofilms protect embedded microorganisms from external threats. A reduction of biofilms in infected wounds is thus advantageous for the healing process. Experimental studies have shown rapid formation of biofilms within 24 hours (3). Therefore an effective therapy to ensure continuous reduction of biofilms must be performed at least twice a day. Tap water could be the solution, which ensures cleaning of the wound by washing out a large part of the biofilm. Removal of the components required for microbial growth leads to a reduction of the pathogenic characteristics of the wound surface. There are several strategies to reduce biofilms in infected wounds. A new approach to minimise cell growth was shown with near-infrared laser on monoand polymicrobial biofilms produced by Staphylococcus aureus and Pseudomonas aeruginosa (4). Hydrosurgery is a rapid and cost-effective system, which appears to be well-tolerated and patients can be successfully treated at the bedside (5). The use of ultrasound for improved wound healing compared with standard wound care alone was shown on patients with leg ulcers of various aetiologies (6). All these strategies aim at a high elimination of bacterial colonies by reducing the biofilm along with all its components. Breaking the biofilm’s physical protection against host inflammatory cells and antibiotic penetration by its self-secreted extracellular substance is a basis for improved wound healing. There is still a limited understanding of biofilms, which remains a challenge for researchers today (7). Acknowledging that problem, the pharmaceutical industry made huge financial efforts associated with chronic wound management. Hydrogel dressings appear to be an easy way of addressing poor wound healing. In fact, it is an essential component in many different types of wound care. Designed to hold moisture on the surface of the wound, it provides an ideal environment by cleaning the wound and allowing the body to rid itself of necrotic tissue. With its high moisture content it helps to prevent bacteria from reaching the wound, thereby providing a barrier for infections. On the other hand, it ensures an ideal environment for bacteria embedded in biofilms working as a kind of bioreactor. This condition can lead to a severe enlargement of the wound. Infected wounds treated with hydrogel dressings showed a massive growth of S. aureus within 24 hours (8). We found that in patients with beginning-stage ulcers treated with hydrogel dressings for several weeks, the wound area increased. Patients with poor wound healing at our institution are treated with tap water few times a day. The frequent elimination of polysaccharides, proteins and lipids reduces the breeding ground for bacterial growth. The irrigation with tap water turned out to be very effective by preventing an enlargement of the wound area. It does not aim at getting the wound sterile, but it is a prerequisite for following therapies.