Biocompatibility and Safety Assessment of Combined Topical Ozone and Antibiotics for Treatment of Infected Wounds

Wound infections with antibiotic-resistant bacteria,particularlythe Gram-negative strains, pose a substantial health risk for patientswith limited treatment options. Recently topical administration ofgaseous ozone and its combination with antibiotics through portablesystems has been demonstrated to be a promising approach to eradicatecommonly found Gram-negative strains of bacteria in wound infections.However, despite the significant impact of ozone in treating the growingnumber of antibiotic-resistant infections, uncontrolled and high concentrationsof ozone can cause damage to the surrounding tissue. Hence, beforesuch treatments could advance into clinical usage, it is paramountto identify appropriate levels of topical ozone that are effectivein treating bacterial infections and safe for use in topical administration.To address this concern, we have conducted a series of in vivo studiesto evaluate the efficacy and safety of a portable and wearable adjunctozone and antibiotic wound therapy system. The concurrent ozone andantibiotics are applied through a wound interfaced gas permeable dressingcoated with water-soluble nanofibers containing vancomycin and linezolid(traditionally used to treat Gram-positive infections) and connectedto a portable ozone delivery system. The bactericidal properties ofthe combination therapy were evaluated on an ex vivo wound model infectedwith Pseudomonas aeruginosa, a commonGram-negative strain of bacteria found in many skin infections withhigh resistance to a wide range of currently available antibiotics.The results indicated that the optimized combination delivery of ozone(4 mg h(-1)) and topical antibiotic (200 mu gcm(-2)) provided complete bacteria eradication after6 h of treatment while having minimum cytotoxicity to human fibroblastcells. Furthermore, in vivo local and systemic toxicity studies (e.g.,skin monitoring, skin histopathology, and blood analysis) on pig modelsshowed no signs of adverse effects of ozone and antibiotic combinationtherapy even after 5 days of continuous administration. The confirmedefficacy and biosafety profile of the adjunct ozone and antibiotictherapy places it as a strong candidate for treating wound infectionwith antimicrobial-resistant bacteria and further pursuing human clinicaltrials.