Date of Award

Spring 4-25-2023

Document Type

Honors Project

Degree Name

Bachelor of Science


Biological Sciences

Department Chair or Program Director

Lewis, Lynn

First Advisor

Lewis, Lynn

Second Advisor

O'Dell, Deborah

Third Advisor

Agrawal, Swati

Major or Concentration



Cancer chemotherapy compromises the patient’s oral health through dysbiosis of oral microbiota and increases the prevalence of dental cavities, gingivitis, oral mucositis, and xerostomia. This research aimed to evaluate the effect of a common chemotherapeutic agent, Fluorouracil (5-FU), on certain microorganisms that are common within the oral cavity. Varying concentrations (50 μM, 75 μM and 100μM) of 5-FU were used to simulate the dosage that reaches the oral cavity after intravenous delivery. The microorganisms tested were Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Lactobacillus rhamnosus and Streptococcus salivarius. These are some of the most common ones found in the diverse oral microbiota and would, therefore, be beneficial to study. Some are associated with different oral conditions like periodontitis, the progression of cavities and lesions, and inflammation, while others are probiotics. There are topical and oral products that can be applied or consumed in order to prevent the overgrowth of certain bacteria, while also protecting the oral mucosa. In evaluating the effect of 5-FU on the microorganisms, two preventative treatments were tested in order to reduce and/or improve their effect on a patient’s oral cavity: chlorhexidine (CHX) and salt water. 5-FU altered all microbial growth curves, yet it least affected P. aeruginosa, S. mutans and S. salivarius. CHX was successful in preventing the growth of most pathogenic bacteria, except P. aeruginosa, and all non-pathogenic bacteria, while salt encouraged the growth of probiotic L. rhamnosus and pathogenic P. aeruginosa yet suppressed the growth of most pathogenic microbes.