Postantibiotic effect of disinfection treatment by photolysis of hydrogen peroxide

Abstract

The purpose of the present study was to evaluate the postantibiotic effect (PAE) of the disinfection treatment by photolysis of H₂O₂. Postantibiotic effect was induced in Staphylococcus aureus and Streptococcus salivarius by exposing the bacteria to H₂O₂ at concentrations of 250–1000 mmol/l, laser irradiation at a wavelength of 405 nm, and the combination of both (photolysis of H₂O₂) for 10–30 seconds. The photolysis of H₂O₂ induced significantly longer PAE than other treatments. The PAE was augmented dependently on not only the concentration of H₂O₂ but the laser irradiation time. Electron spin resonance analysis showed that the hydroxyl radical was also generated dependently on both the concentration of H₂O₂ and the laser irradiation time, suggesting that the hydroxyl radicals contribute to the PAE. These results suggest that the disinfection treatment by photolysis of H₂O₂ induces PAE in S. aureus and S. salivarius even though they were treated for only 10–30 seconds.

Keywords:

• Bacterial growth inhibition
• Disinfection treatment
• Hydrogen peroxide
• Hydroxyl radical
• Photolysis
• Postantibiotic effect

Acknowledgements

This research was partially supported by the Ministry of Education, Science, Sports, and Culture of Japan (Grant-in-Aid for Scientific Research (B), 22390362, 2010, and by the grant for The 11th Intelligent Cosmos Encouragement Prize from Intelligent Cosmos Academic Foundation, 2012.