Antibacterial efficacy of essential oils of three aromatic plants in combination with povidone-iodine against Staphylococcus aureus grown in biofilm cultures.

ABSTRACT

Staphylococcus aureus, one of the opportunistic species responsible for clinical and / or bacteriological infections may react with biotic and abiotic surfaces and produces biofilm. In this form the bacteria become somewhat vulnerable to various physical and / or chemical antimicrobial agents. The aim of this study was to investigate the antibacterial efficacy of PVI, alone and in combination with essential oils (EO) of three aromatic plants, Eucalyptus globulus, Thymus capitatus, and Rosmarinus officinalis, against biofilms of four clinical isolates of Staphylococcus aureus from intravenous catheter associated infections. These strains isolated at the university hospital of Tlemcen, were characterized and identified, in a previous study, as strongly adherent using the microtiter plate method. Minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations of different essential oils sole and in combination with PVI for studied strains grown in biofilm, were determined by microbroth dilution method. The antibacterial effect of EOs and PVI, alone and in combination, against biofilmforming staphylococci, was also demonstrated. EO of E. globulus was more effective, in comparaison with the two other EOs. In addition, the antibacterial effects of the three EOs studied in combination with PVI were deemed synergistic against the biofilm of all tested strains, with a fractional inhibitory concentration index (FICI) <0.5. Accordingly, we could suggest the use of PVI in combination with EOs, especially of E. globulus ; since this EO was proved to be more efficacious in enhancing the antibacterial efficacy of PVI against biofilm of S. aureus.