High efficacy of ozonated oils on the removal of biofilms produced by methicillin-resistant staphylococcus aureus (MRSA) from infected diabetic foot ulcers

© 2020 by the authors. Ozone has a high wound healing capacity and antibacterial properties and can be used as a complementary treatment in infections. Methicillin-resistant S. aureus (MRSA) is the most common pathogen found in infected diabetic foot ulcers. Most of MRSA are resistant to several classes of antibiotics and, therefore, there is a need for new, effective, and well-tolerated agents. Thus, we aimed evaluate the antimicrobial and antibiofilm potentials of ozonated vegetable oils against MRSA strains isolated from diabetic foot ulcers. Six ozonated oils were produced with concentrations of ozone ranging from 0.53 to 17 mg of ozone/g of oil. The peroxide values were determined for each oil. Ozonated oils content on fatty acid was determined by gas chromatography equipped with a flame ionization detector. The antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method and the effect of ozonated oils on biofilm formation ability and on established biofilms was investigated. In general, the content in identified unsaturated fatty acid in oils decreased with the increase of ozonation time and, consequently, the peroxide value increased. Most bacterial strains were inhibited by ozonated oil at a concentration of 4.24 mg/g. Ozonated oils had moderate to high ability to remove adhered cells and showed a high capacity to eradicate 24 h old biofilms. Our results show promising use of ozonated oils on the treatment of infections, in particular those caused by multidrug-resistant MRSA strains.This work was funded by the R&D Project CAREBIO2—Comparative assessment of antimicrobial resistance in environmental biofilms through proteomics—towards innovative theranostic biomarkers, with reference NORTE-01-0145-FEDER-030101 and PTDC/SAU-INF/30101/2017, financed by the European Regional Development Fund (ERDF) through the Northern Regional Operational Program (NORTE 2020) and the Foundation for Science and Technology (FCT). This work was supported by the Associate Laboratory for Green Chemistry—LAQV, which is financed by national funds from FCT/MCTES (UIDB/50006/2020). Joana S. Amaral is grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020). Vanessa Silva is grateful to FCT (Fundação para a Ciência e a Tecnologia) for financial support through PhD grant SFRH/BD/137947/2018.info:eu-repo/semantics/publishedVersio

Chemical characterization and antimicrobial activity of ozonized oil against methicillin resistant Staphylococcus aureus

Methicillin resistant Staphylococcus aureus (MRSA) are frequently found in infected skin wounds due to the exposure of deep tissues to the bacteria, in particular in infected diabetic foot ulcers in which the prevalence can be between 15 to 40% [1]. Clinical MRSA are usually resistant to most classes of antibiotics and, therefore, it is necessary to investigate new antimicrobial agents. Ozone has a recognized bactericidal activity and has been widely used as a clinical therapeutic agent for chronic wounds, such as, ulcers and other diabetic lesions, due to its wound healing ability [2]. This study aimed to characterize ozone oil suspensions and their activity against MRSA isolated from infected diabetic foot ulcers. Six ozonized oils with different ozonization doses were tested by disk diffusion method. The oils were prepared from a 50:50 mixture of extra virgin olive oil and refined sunflower oil and submitted to a gas stream of O2/O3 mixture at a concentration of 75 μg/ml of ozone in continuous flow (4 L/min). The oil content in fatty acid methyl esters after ozonization were investigated using a Bruker® SCION 436-GC gas chromatograph equipped with a flame ionization detector (GC-FID). All ozone suspension oils tested showed antimicrobial activity against all strains. The ozone suspension oil with the highest ozonization dose originated clear zones with a maximum of 12 mm. Composition of fatty acids in ozonized oils showed gradual decrease in unsaturated fatty acids with gradual increase in ozone doses. Overall, there was a decrease in the total fatty acid investigated and an increase in the content of unknown oxidized fatty acid with the increase of ozonization period. Our results indicate that ozonized oils have a significant antimicrobial activity, however, it is still unclear which compounds may be responsible for the bactericidal action.Vanessa Silva is grateful to FCT (Fundação para a Ciência e Tecnologia) for her PhD grant SFRH/BD/137947/2018info:eu-repo/semantics/publishedVersio