# Carbonic anhydrase inhibition as a target for antibiotic synergy in enterococci

> **NIH NIH R03** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2024 · $79,500

## Abstract

SUMMARY
Enterococcus faecalis is a hospital-associated opportunistic pathogen that causes infections with high
morbidity and mortality. An increasing occurrence of multidrug-resistant enterococci has driven the
need for alternative treatment strategies to combat these pathogens. In this proposal, we describe the
isolation and characterization of an unusual gentamicin hypersusceptible E. faecalis strain that was
cultured from a patient with infective endocarditis. We performed an in vitro resistance selection with
this E. faecalis strain to generate one-step (i.e. single mutation) mutants that displayed wild type
gentamicin susceptibility levels. Whole-genome sequencing of the one-step mutants showed that
gentamicin hypersusceptibility in the parent strain was caused by a mutation that disrupted the E.
faecalis alpha-carbonic anhydrase. Separately, we observed that the carbonic anhydrase inhibitor
acetazolamide and gentamicin together displayed synergistic activity at inhibiting the growth of wild
type E. faecalis strains. This finding has led us to hypothesize that disruption of carbonic anhydrases
can sensitize E. faecalis to killing with aminoglycosides. To determine the mechanistic basis of this
synergy, we will examine whether disruption of the E. faecalis alpha-carbonic anhydrase causes
increased gentamicin uptake via proton motive force-dependent transport and/or increased membrane
permeability (Aim 1). In addition, we will investigate differential synergy between aminoglycosides and
chemically diverse carbonic anhydrase inhibitors against isogenic E. faecalis strains expressing
different carbonic anhydrase genotypes (Aim 2). This is the first time that a connection between
carbonic anhydrase disruption and bacterial membrane energization or permeability will be
investigated. Successful completion of this project will increase our understanding of E. faecalis biology,
while also providing important pilot data toward the development of a promising new combination
therapy for patients with enterococcal infections.

## Key facts

- **NIH application ID:** 10739803
- **Project number:** 5R03AI168491-02
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Daria N Van Tyne
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $79,500
- **Award type:** 5
- **Project period:** 2022-11-14 → 2024-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10739803

## Citation

> US National Institutes of Health, RePORTER application 10739803, Carbonic anhydrase inhibition as a target for antibiotic synergy in enterococci (5R03AI168491-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10739803. Licensed CC0.

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