Effect of low-dose gaseous ozone on pathogenic bacteria

<p>Abstract</p> <p>Background</p> <p>Treatment of chronically infected wounds is a challenge, and bacterial environmental contamination is a growing issue in infection control. Ozone may have a role in these situations. The objective of this study was to determine whether a low dose of gaseous ozone/oxygen mixture eliminates pathogenic bacteria cultivated in Petri dishes.</p> <p>Methods</p> <p>A pilot study with 6 bacterial strains was made using different concentrations of ozone in an ozone-oxygen mixture to determine a minimally effective dose that completely eliminated bacterial growth. The small and apparently bactericidal gaseous dose of 20 μg/mL ozone/oxygen (1:99) mixture, applied for 5min under atmospheric pressure was selected. In the 2^nd phase, eight bacterial strains with well characterized resistance patterns were evaluated <it>in vitro</it> using agar-blood in adapted Petri dishes (10⁵ bacteria/dish). The cultures were divided into 3 groups: 1- ozone-oxygen gaseous mixture containing 20 μg of O₃/mL for 5 min; 2- 100% oxygen for 5 min; 3- baseline: no gas was used.</p> <p>Results</p> <p>The selected ozone dose was applied to the following eight strains: <it>Escherichia coli</it>, oxacillin-resistant <it>Staphylococcus aureus</it>, oxacillin-susceptible <it>Staphylococcus aureus</it>, vancomycin-resistant <it>Enterococcus faecalis</it>, extended-spectrum beta-lactamase-producing <it>Klebsiella pneumoniae</it>, carbapenem-resistant <it>Acinetobacter baumannii</it>, <it>Acinetobacter baumannii</it> susceptible only to carbapenems, and <it>Pseudomonas aeruginosa</it> susceptible to imipenem and meropenem. All isolates were completely inhibited by the ozone-oxygen mixture while growth occurred in the other 2 groups.</p> <p>Conclusion</p> <p>A single topical application by nebulization of a low ozone dose completely inhibited the growth of all potentially pathogenic bacterial strains with known resistance to antimicrobial agents.</p