title: Efficacy of a Low Dose of Hydrogen Peroxide (Peroxy Ag⁺) for Continuous Treatment of Dental Unit Water Lines: Challenge Test with Legionella pneumophila Serogroup 1 in a Simulated Dental Unit Waterline.
abstract: This study was designed to examine the in vitro bactericidal activity of hydrogen peroxide against Legionella. We tested hydrogen peroxide (Peroxy Ag⁺) at 600 ppm to evaluate Legionella survival in a simulated dental treatment water system equipped with Water Hygienization Equipment (W.H.E.) device that was artificially contaminated. When Legionella pneumophila serogroup (sg) 1 was exposed to Peroxy Ag⁺ for 60 min we obtained a two decimal log reduction. High antimicrobial efficacy was obtained with extended periods of exposure: four decimal log reduction at 75 min and five decimal log reduction at 15 h of exposure. Involving a simulation device (Peroxy Ag⁺ is flushed into the simulation dental unit waterlines (DUWL)) we obtained an average reduction of 85% of Legionella load. The product is effective in reducing the number of Legionella cells after 75 min of contact time (99.997%) in the simulator device under test conditions. The Peroxy Ag⁺ treatment is safe for continuous use in the dental water supply system (i.e., it is safe for patient contact), so it could be used as a preventive option, and it may be useful in long-term treatments, alone or coupled with a daily or periodic shock treatment.
authors.affiliation: Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy. savina.ditommaso@unito.it.
authors.forename: Savina
authors.initials: S
authors.lastname: Ditommaso
authors.affiliation: Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy. monica.giacomuzzi@unito.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Giacomuzzi
authors.affiliation: Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy. elisa.ricciardi@unito.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Ricciardi
authors.affiliation: Department of Public Health and Pediatrics, University of Turin, Turin 10126, Italy. carla.zotti@unito.it.
authors.forename: Carla M
authors.initials: CM
authors.lastname: Zotti
mesh_terms: D003748:Dental Equipment; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016952:Legionella pneumophila / Q000187:drug effects*; D065288:Serogroup; D012834:Silver / Q000494:pharmacology*; D014867:Water; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D014867:Water; D012834:Silver; D006861:Hydrogen Peroxide
keywords: Legionella; biofilm; dental infection control; disinfectants; hydrogen peroxide (H2O2); microbial sensitivity test