title: Mechanism of Sporicidal Activity for the Synergistic Combination of Peracetic Acid and Hydrogen Peroxide.
abstract: There is still great interest in controlling bacterial endospores. The use of chemical disinfectants and, notably, oxidizing agents to sterilize medical devices is increasing. With this in mind, hydrogen peroxide (H2O2) and peracetic acid (PAA) have been used in combination, but until now there has been no explanation for the observed increase in sporicidal activity. This study provides information on the mechanism of synergistic interaction of PAA and H2O2 against bacterial spores. We performed investigations of the efficacies of different combinations, including pretreatments with the two oxidizers, against wild-type spores and a range of spore mutants deficient in the spore coat or small acid-soluble spore proteins. The concentrations of the two biocides were also measured in the reaction vessels, enabling the assessment of any shift from H2O2 to PAA formation. This study confirmed the synergistic activity of the combination of H2O2 and PAA. However, we observed that the sporicidal activity of the combination is largely due to PAA and not H2O2. Furthermore, we observed that the synergistic combination was based on H2O2 compromising the spore coat, which was the main spore resistance factor, likely allowing better penetration of PAA and resulting in the increased sporicidal activity.
authors.affiliation: Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Leggett
authors.affiliation: Steris Corporation, St. Louis, Missouri, USA.
authors.forename: J Spencer
authors.initials: JS
authors.lastname: Schwarz
authors.affiliation: Steris Corporation, Mentor, Ohio, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Burke
authors.affiliation: Steris Corporation, Mentor, Ohio, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: McDonnell
authors.affiliation: Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Denyer
authors.affiliation: Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom maillardj@cardiff.ac.uk.
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Maillard
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004357:Drug Synergism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects*; D010463:Peracetic Acid / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D006861:Hydrogen Peroxide; D010463:Peracetic Acid