Abstract

The proliferation of antibiotic resistant microbes is a direct response to evolutionary pressure Microbes live and die on a rapid time scale that allows for evolution to occur at an accelerated rate. Decades of antibiotic use, often overuse, has provided adequate time for microbes to develop resistance mechanisms. The lack of profitability coupled with resistant microbes has created an urgency to develop new antibiotics. Plant based essential oils have an extensive history as antimicrobial agents that can be linked to their phenol or phenol-like compounds. The balance of both hydrophilic and hydrophobic regions of the phenols allow them to act as membrane permeabilizers. Disruption of the cellular membrane causes the cell to leak components in addition to preventing the gradients required for the cell to function properly. Gas chromatography-mass spectroscopy was used to confirm the presence of phenols in oregano and cinnamon bark essential oil. There are multiple different essential oils that display antimicrobial properties with a minimum inhibitory concentration (MIC) at dilutions of 0.125% but oregano oil (Origanum vulgare) and cinnamon bark oil (Cinnamomum cassia Blume) inhibit Gram-negative Escherichia. coli, Gram-positive Staphylococcus aureus, and methicillin-resistant S. aureus at concentrations as low as 0.031%. The use of Gram-positive and Gram-negative strains are used to represent the two major classes of bacteria. Additionally, Cinnamon bark and oregano oil retained a low MIC in the presence of 10% and 50% human serum. Essential oils and their active components provide a source for antibiotic development.