Honors Theses

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Date of Award

2022

Document Type

Honors Thesis - NSU Access Only

Department

Halmos College of Arts and Sciences and the Guy Harvey Oceanographic Research Center

Honors College

Farquhar Honors College Thesis

Honors College Dean

Andrea Nevins, Ph.D.

Home College Dean

Holly Baumgartner, Ph.D.

Faculty Advisor

Robert Smith, Ph.D.

Abstract

The inoculum effect (IE) is a phenomenon in which the minimal inhibitory concentration (MIC) of an antibiotic increases with the initial density of a bacterial population. IE has been observed for nearly all antibiotics, and has been shown to decrease antibiotic efficacy, prolong recovery periods, and increases mortality rates of hosts. Despite its ubiquity in the clinic, a mechanism to explain IE for bacteria that expresses antibiotic resistant elements, such as β-lactamases, has yet to be identified. Interestingly, recent work has shown that interactions between growth rate and metabolism, as determined through ATP production, affect IE for bacteria that lack a genetically encoded resistance mechanism. While interactions between growth and metabolism could explain IE for βlactamase producing bacteria, this has yet to be explored. Therefore, this study was focused on understanding the relationship between ATP and IE produced by bacteria that express β-lactamase. We found that changing the expression rate of β-lactamase via IPTG induction changed the amount of ATP produced; this also altered the severity of IE. Specifically, we found that increasing the amount of ATP produced reduced the strength of IE. This could be accomplished by manipulating either β-lactamase expression or carbon source in the growth medium, both of which affected ATP production. Overall, our results may help us develop novel approaches to treating bacterial infections in the clinic with future patients.

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