Graduation Year

2016

Date of Submission

5-2016

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Biology

Reader 1

Suzanne Kern

Reader 2

Jennifer Armstrong

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Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2016 Geneviève A. Donahey

Abstract

Due to high rates of emerging antibiotic resistant bacteria, research into combatting these “superbugs” has focused on engineering more effective treatments for bacterial infections, including pairing antibiotics having varied mechanisms of action to elicit a stronger antimicrobial response than a single antibiotic treatment. Previous studies have characterized pairwise antibiotic interactions as having synergistic, additive, or antagonistic relationships, suggesting the possibility that many factors influence the resulting response. As an extension of the research done on paired antibiotic interactions, this work endeavored to examine whether changing nutritional environments had an effect on documented synergistic relationships between various groups of antibiotics. To corroborate previous studies, antibiotics from the β lactam (targeting cell wall synthesis) and aminoglycoside (targeting protein synthesis) families were chosen as test subjects and paired with antibiotics from other classes under varied nutrient conditions. Streptomycin (STR) and Amikacin (AMK) were two aminoglycosides tested in their relationship to Ciprofloxacin (CPR), a fluoroquinolone (targeting DNA replication). The relationships between the aminoglycosides and CPR remained consistently synergistic in various media, including two complex, undefined media, LB and yeast extract (YE), and dilution of both media with a saline solution to half-strength. In contrast, the selected β lactams Piperacillin (PIP) and Ampicillin (AMP) did not show a previously documented synergy with the macrolide (targeting protein synthesis) Erythromycin (ERY), and alterations to the culture medium vastly affected the PIP/ERY combined relationship. Collectively, these results suggest that antibiotic interactions are not based on a singular mechanism, and that these relationships may be able to be manipulated through environmental factors such as changing nutritionalenvironments. A multi-faceted pathway for manipulating drug interactions may be key in increasing the efficacy of antibiotic treatment plans.

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