Antibacterial and antibiofilm activity of some essential oils and compounds against clinical strains of Staphylococcus aureus

Increased emergence and spread of multidrug resistant bacteria including methicillin resistant S. aureus (MRSA) and their biofilms have created immense clinical problem in treatment of bacterial diseases. Biofilms are difficult to eradicate with standard antimicrobial treatments due to high antibiotic resistance level compared to free living cells.  Biofilm formation by isolated S.aureus was first assayed by macro tube and microtitre plate assays. We demonstrate here that the selected essential oils and some of their compounds (eugenol, cinnamaldehyde,citral and geraniol) showed varying levels of antibacterial activity and sub-MICs of these agents effectively inhibit biofilm formation of Staphylococcus aureus strains. The order of antibacterial activity was found as T. vulgaris > S. aromaticum > eugenol> cinnamaldehyde> citral> C. citratus > C. martini > geraniol> C. nardus . The antibofilm activity of tested oil ( Thymus vulgaris ) and compounds (eugenol) at 2xMIC values indicated their potential therapeutic application alone or in combination with antibiotics for treating biofilm assocated clinical problems caused by Staphylococcus aureus