Battling the Biofilm: Topical Oxygen Shifts the Bacterial Biofilm Community in Chronic Wounds

Biofilms in wounds prevent healing by both acting as a physical barrier to wound closure, and hyper-activing local inflammatory processes. Eradicating wound biofilms is therefore a therapeutic priority. However, bacteria living as a biofilm are phylogenetically diverse, semi-dormant and matrix-embedded, and are therefore highly resistant to antibiotic therapy. To underscore the problem, clinical diagnostic microbiology uses traditional culture-based systems that miss up to 99% of bacteria present in a wound biofilm. We have previously used topical oxygen as an adjunctive therapy for chronic wounds with great success, and hypothesized that this therapy could also be affecting the bacterial species composition in wound biofilms. In this study, we used 16S rDNA metagenomic sequencing to track the organisms present in 6 chronic wounds over the course of therapy with topical oxygen for 8 weeks. We found that almost 100% of the flora was anaerobic (or facultatively anaerobic) prior to topical oxygen application, and underwent a striking shift to an aerobic flora dominated by Staphylococci, Streptococci and Corynebacterium following 2 weeks of topical oxygen. These results offer the first evidence that topical oxygen helps chronic wounds by altering the bacterial biofilm.