Disinfection of Pseudomonas aeruginosa-infected wounds in diabetic db/db mice by weakly acidic hypochlorous acid

Background Weakly acidic hypochlorous acid (HOCl), a major inorganic bactericidal compound of innate immunity, is effective against a broad range of microorganisms. However, HOCl has never been described as a pharmaceutical drug for treatment of infected wounds. Here, we describe a study using HOCl solution, a reagent that has potential use in a clinical situation such as prevention and treatment of infection in chronic wounds. Methods HOCl solution (200 ppm, pH 6.5) was prepared by the in vitro addition of sodium hypochlorite to sterile water or saline at pH 6.5. The resulting solutions were used to evaluate in vitro cytotoxic and bacteriostatic properties against Pseudomonas aeruginosa. Furthermore, the bacteriostatic effect of the HOCl solutions was evaluated in vivo using P. aeruginosa-infected wounds on db/db diabetic mice. Results The HOCl solution exhibited concentration-dependent in vitro bacteriostatic activity against P. aeruginosa; HOCl in phosphate-buffered saline (PBS) also displayed in vitro cytotoxicity to human fibroblasts. Similarly, the cleansing of P. aeruginosa-infected wounds on db/db diabetic mice with HOCl solution yielded significantly decreased in vivo bacterial cell counts and there was no difference in granulation formation compared to cleansing with pure water. Conclusion Twelve days of once-daily cleansing of P. aeruginosa-infected wounds on db/db diabetic mice with HOCl solution resulted in significantly decreased P. aeruginosa bioburden, albeit with a minor delay in wound repair.