All ETDs from UAB

Advisory Committee Chair

Olaf Kutsch

Advisory Committee Members

Frank Wolschendorf

Terje Dokland

Hui Wu

William Swords

Document Type

Dissertation

Date of Award

2020

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

The effective antibiotic pool is shrinking with antibiotic resistance a constant problem that threatens to make our current therapies obsolete. To combat this, new drug screening methodologies are required since the traditional drug screens are offering limited results or only improvements upon current treatments. This work expands upon the idea that transition metal toxicity can be preferentially targeted towards bacteria. Specifically, the focus is on copper dependent inhibitors that quickly work to eliminate Staphylococcus aureus. S. aureus is a particularly threatening bacteria with high strain variability, a litany of survival and virulence factors, and multiple drug resistance mechanisms that are quick to develop and spread. This has allowed it to enter both hospital and community environments, as well as have a high resistance rate against the first line of defense antibiotics. To help combat S. aureus, we have utilized screening conditions that preferentially discover inhibitors that utilize copper to uncover the pyrazolopyrimidinones (PZPs) and NNSNs. Our work has uncovered the rapid killing of S. aureus by these copper dependent inhibitors (CDIs) that is irrespective of biofilm formation or common drug resistance mechanisms. The bactericidal effects stem from the ability of CDIs to drastically increase the copper concentration within the bacteria. We hypothesize that this causes a rapid depolarization of the bacterial membrane and copper concurrently inhibits GAPDH. The result is a rapid decline in ATP concentrations followed by bacterial death. Specifically, for the NNSNs, this activity is abrogated by the presence of additional copper resistance genes in the form of copX and copL. However, when the NNSNs are combined with ampicillin, both drugs can overcome their respective drug resistance. Strains that were resistant to NNSNs become sensitive and the same happened for strains recalcitrant to ampicillin treatment. Overall, we show that CDIs are a potent alternative to current therapies and could potentially be used to revive antibiotics that have fallen out of use due to drug resistance.

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