Essential oils with microbicidal and antibiofilm activity.

Plants are rich in a wide variety of secondary metabolites with antimicrobial properties. Phytochemistry studies on the plants extracts in general, and on essential oils (EOs) in particular are focused on the isolation and identification of the components of complex mixtures, in order to determine structure - activity correlations (i.e., physiological and/ or ecological roles, bases for the pharmacognosy studies). Problems as microbial resistance to existing antibiotics and the decline in the formulation of new antibiotics generated an increased interest in anti-infective herbal medicines. Some plants are known to be EOs producing, especialy superior plants, angiosperms and gymnosperms, belonging to approximately 50 families, most frequently Apiaceae, Lamiaceae, Myrtaceae, Pinaceae, Zingiberaceae, etc. The antimicrobial activity of EOs and of their components has been demonstrated on a variety of microorganisms. Our aim was to review relevant literature for identifying current research directions regarding EOs, in terms of antimicrobial effects, analysismethods and mechanisms of action. A plethora of methods have been used to test EOs antimicrobial properties concerning the microbial growth inhibition and/ or their anti-pathogenic effect. The reported methods contributed also to the elucidation of their mechanisms of action. Future research is needed for developing EOs related strategies in overlapping the multi-drug resistance and for reducing the required concentrations to achieve a particular antimicrobial and/ or antibiofilm effect to the human health benefit and/or for food safety purposes.