Date of Award

6-2022

Document Type

Open Access

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Robert Lauzon

Keywords

E. coli, Microbiology, antimicrobial, bacteriophage, phage, resistance

Abstract

The increasing prevalence of antibiotic-resistant bacteria is an emerging problem for humans. Clinical misuse, overuse in agricultural and food settings, and limited numbers of new antibiotics have accelerated the proliferation of antibiotic-resistant bacteria. To confront this threat, scientists must develop new therapeutics that kill these antibiotic-resistant bacteria. In this study, we used Escherichia coli to analyze antibiotic and bacteriophage susceptibility. E. coli is a common, mostly benign, enteric, gram-negative bacteria. We isolated three E. coli strains from the Hans Groot Kill, a stream that runs through Union College’s campus. We sought to assess various E. coli strains’ antibiotic resistance, susceptibility to bacteriophages, and underlying resistance mechanisms. We compared the environmental E. coli isolates to known lab strains of E. coli. Using T4 bacteriophage, a well characterized viral pathogen that carries out a lytic cycle in E. coli bacteria, we conducted modified plaque assays with the three environmental isolates and lab strains “B” and “C.” The environmental isolates were found to be highly resistant to T4 phage, while the lab strains were susceptible. We also conducted Kirby-Bauer antimicrobial disk susceptibility tests, using various gram-negative targeted drugs. We found the lab strains to be highly susceptible to all of the antibiotics, while the environmental isolates showed intermediate resistance to some of the antibiotics. Surprisingly, both environmental and lab strains were encapsulated. These patterns of resistance to phages and antimicrobial drugs suggest that environmental E. coli strains must have some mechanism for resistance that could be exploited as a novel means of treating drug-resistant infections.

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Rights Statement

In Copyright - Educational Use Permitted.