title: Effect of low-dose gaseous ozone on pathogenic bacteria.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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 5 min under atmospheric pressure was selected. In the 2nd phase, eight bacterial strains with well characterized resistance patterns were evaluated in vitro 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 O(3)/mL for 5 min; 2--100% oxygen for 5 min; 3--baseline: no gas was used.
  
  
  RESULTS
  The selected ozone dose was applied to the following eight strains: Escherichia coli, oxacillin-resistant Staphylococcus aureus, oxacillin-susceptible Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, carbapenem-resistant Acinetobacter baumannii, Acinetobacter baumannii susceptible only to carbapenems, and Pseudomonas aeruginosa susceptible to imipenem and meropenem. All isolates were completely inhibited by the ozone-oxygen mixture while growth occurred in the other 2 groups.
  
  
  CONCLUSIONS
  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.
authors.affiliation: 3rd Division of Clinical Surgery and Laboratory of Medical Investigation (LIM-62), Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
authors.forename: Belchor
authors.initials: B
authors.lastname: Fontes
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Cattani Heimbecker
authors.forename: Glacus
authors.initials: G
authors.lastname: de Souza Brito
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Costa
authors.forename: Inneke M
authors.initials: IM
authors.lastname: van der Heijden
authors.forename: Anna S
authors.initials: AS
authors.lastname: Levin
authors.forename: Samir
authors.initials: S
authors.lastname: Rasslan
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D004202:Disinfectants / Q000494:pharmacology*; D005740:Gases / Q000494:pharmacology*; D050296:Microbial Viability / Q000187:drug effects; D010126:Ozone / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D004202:Disinfectants; D005740:Gases; D010126:Ozone