How much ozone bactericidal activity is compromised by plasma components?

Aims:  Evaluation of bactericidal effect of different concentrations of ozone when used (a) as a gas, or (b) dissolved in saline. The addition of hydrogen peroxide or 4-hydroxynonenal dissolved in saline was also tested, as well as the effect of human plasma.
Methods and Results:  Staphylococcus aureus , methicillin-resistant Staph. aureus (MRSA), and Pseudomonas aeruginosa , suspended in their culture media were tested. While all bacteria suspended in protein-free saline were killed at high ozone concentrations, they survived when as little as 5% human plasma was present. Hydrogen peroxide was 100-fold less active than ozone and needed to remain in contact with bacteria for at least 60 min. 4-hydroxynonenal (2 μmol l⁻¹) was inhibitory for proliferation of both Staph. aureus and MRSA, but not for Ps. aeruginosa .
Conclusions:  Ozone and the cascade of its derivative products are potent bactericidal agents, but even small amounts of human plasma, hence of hydro- and liposoluble antioxidants, in bacterial suspensions inhibit oxidation and protect bacteria.
Significance and Impact of the Study:  Any substantial in vivo cytocidal effect of ozone and its derivatives can be excluded. On the other hand, topical and continuous action of various ozone preparations remains valuable in a variety of skin and mucosal infections.