[IMPACT OF BIOFILM ON HEALING AND A METHOD FOR IDENTIFYING IT IN THE WOUND]

Abstract

The skin microbiome is the aggregate of microorganisms that reside on the surface and in deep layers of the skin. Skin is colonized by bacteria, fungi, viruses and mites, maintaining a balance. Disruption in the ecosystem results in skin infections. Chronic wounds in diabetics, elderly and immobile individuals are at risk of skin organisms to invade and become pathogenic upon breach of the skin barrier. The bacteria of the skin microbiome may contribute to delayed healing and persistent inflammation. Staphylococcus epidermidis is an invasive skin organism that causes infection, i.e. hospital acquired infection (HAl) on medical devices and form biofilm. At the most basic level, biofilm can be described as bacteria embedded in a thick, slimy barrier of sugars and proteins. The biofilm barrier protects the microorganisms from external threats. Biofilms provide a reservoir of potentially infectious microorganisms that are resistant to antimicrobial agents, and their importance in the failure of medical devices and chronic inflammatory condition is increasingly being recognized. Particular research interest exists in the association of biofilms with wound infection and non-healing, i.e. chronic wounds. There is now strong evidence that biofilm is present in the majority of chronic wounds. Specialized microscopic techniques used since 2008 have allowed several research groups to demonstrate that 60% to 90% of chronic wounds have biofilm versus only 6% of acute wounds. While many studies confirm that chronic wounds often contain a polymicrobial flora, controversy remains with regard to whether these organisms directly contribute to non-healing. It seems most likely that individual bacteria themselves are not directly responsible for non-healing wounds. Rather, there is direct correlation between the presence of four or more distinct bacterial species in a wound and non-healing, suggesting that mixed microbial populations are the cause of pathology. The most reliable method to confirm the presence of a biofilm is specialized microscopy, e.g., bright-field, fluorescence in situ hybridization (FISH), and environmental scanning electron microscope (ESEM). Surface wound cultures underestimate total wound microbiota--misleading. Histological staining of deep debrided tissue shows evidence of biofilms. Now it is recognized that the majority of microbial species in chronic wounds are anaerobic bacteria (deep swabbing techniques yield similar findings to biopsies) if samples are processed within two hours. Traditional (wound culture method) cultures have limitations because all microbes (the organisms within the biofilm) cannot be isolated in culture or cannot be detected. Therefore, the most effective methods are molecular