Essential Oils and Microbial Communication

The World Health Organization highlighted the increase in the resistance to conventional antibiotics for most pathogens and observed also a decrease of the threshold for all mechanisms of cell-cell microbial communication, leading to the formation of biofilms and to the increase of microbial pathogenicity. Scientific community is therefore oriented to the identification and study of alternative substances to antibiotics. In such context, substances of vegetal source, such as essential oils (EOs), always used in traditional medicine, stimulated—particularly in recent decades—the scientific world to discover and identify substances, intended as a mixture or single components capable to fight pathogenic microorganisms. From this point of view, the study of plants is very interesting and offers many interesting ideas and results. This brief chapter describes the basis of the microbial communication, until the formation of biofilm, and some mechanisms through which essential oils, or some of their main components, may decrease or inactivate the complex mechanisms that lead to pathogenicity, both of prokaryotes and eukaryotes.