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Open Access Research article

Effect of low-dose gaseous ozone on pathogenic bacteria

Belchor Fontes1, Ana Maria Cattani Heimbecker2, Glacus de Souza Brito3, Silvia F Costa4, Inneke M van der Heijden5, Anna S Levin6* and Samir Rasslan7

Author Affiliations

1 3rd Division of Clinical Surgery and Laboratory of Medical Investigation (LIM-62), Hospital das Clínicas, University of São Paulo, São Paulo, Brazil

2 Laboratory of Medical Investigation (LIM-62), Hospital das Clínicas, University of São Paulo, São Paulo, Brazil

3 Clinical Immunology and Allergy Division, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil

4 Department of Infectious Diseases and LIM54, University of São Paulo, São Paulo, Brazil

5 Laboratory of Medical Investigation (LIM-54), Hospital das Clínicas, University of São Paulo, São Paulo, Brazil

6 Departments of Infectious Diseases and Nosocomial Infection Control and LIM54, University of São Paulo, Rua Banibas, 618, São Paulo, SP, 05460-010, Brazil

7 Department of Surgery, University of São Paulo, São Paulo, Brazil

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BMC Infectious Diseases 2012, 12:358  doi:10.1186/1471-2334-12-358

Published: 18 December 2012

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 5min 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 O3/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.

Conclusion

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.

Keywords:
Ozone; Resistant bacteria; in vitro study