The Evaluation of Essential Oils for Antimicrobial Activity

The emergence of antibiotic resistant bacteria is of pressing concern as health care associated infections kill 99,000 people a year in the U.S. alone. Researchers are currently looking for new antibiotics in alternative sources. Essential oils are traditionally known to have medical benefits, and cinnamon, tea tree, and eucalyptus oils have shown antibiotic activity. Initial testing via standard microbiological protocols found minimum inhibitory concentration (MIC) values of 0.039% for cinnamon, 1.25% for tea tree, and 0.313% for eucalyptus. All three oils proved effective against both Gram-positive and Gram-negative bacteria. Cinnamon bark oil, Cinnamomum cassia Blume, appeared most effective. More thorough microbiological analysis revealed it to be bactericidal and retained antibacterial activity in the presence of human serum protein. The results revealed cinnamon bark oil may contain a promising novel antibiotic