Date of Completion


Document Type

Honors College Thesis



Thesis Type

Honors College, College of Arts and Science Honors

First Advisor

Melissa Pespeni

Second Advisor

John Barlow

Third Advisor

Todd Pritchard


antimicrodbial resistance, staphylococcus aureus, alternative therapies, essential oils


Antibiotic resistance is a world health crisis which demands research on alternative antimicrobial compounds. Research shows that many plant essential oils and their individual constituents possess antibacterial, antiviral, and antifungal properties. Here, we assess the likelihood of resistance emerging to Cinnamon Bark oil or Tea Tree oil in Staphylococcus aureus isolates gathered from organic dairy farms in Vermont. Isolates were exposed to sub-lethal levels of the oils over a period of 20 days, and were also exposed to a sub-lethal concentration of Penicillin over a period of 12 days. Isolates exposed to penicillin experienced an increase in their minimum inhibitory concentration (MIC), but there was no change in the tolerance to essential oils. Additionally, while the proportion of resistant individuals increased after exposure to penicillin, the proportion of resistant individuals decreased after exposure to essential oils in two out of three isolates. These findings support continued effort to integrate essential oils into the fight against drug-resistant bacteria in the fields of medicine, agriculture, and food preservation.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.