# Characterization of viridans group streptococci from endophthalmitis

> **NIH NIH R21** · UNIVERSITY OF MISSISSIPPI MED CTR · 2020 · $193,750

## Abstract

Project Summary/Abstract
The viridans streptococci are classically considered oral commensals with cariogenic potential; however, these
bacteria are also listed among the most common species that cause bacterial endophthalmitis. Exogenous
bacterial endophthalmitis can occur following trauma, ocular surgery, or ocular injections. Antibiotics are used
to treat this disease, however, antibiotics are only able to kill the bacteria and do not ameliorate the damage to
the eye. Streptococcal species in particular are associated with very poor visual outcomes; despite treatment,
evisceration or enucleation commonly occur. The immediate objective of this application is to characterize
endophthalmitis strains of the viridans streptococci and identify their virulence factors. This objective is
intended to initiate study into the broader, long-term objectives of determining the mechanisms of pathogenesis
of this important group of species and identify potential targets for future therapies. Two major aims are
proposed: 1) to investigate the role of bacterial protease HtrA in endophthalmitis and determine its vitreous and
bacterial protein substrates, and 2) to analyze the pangenome and virulence transcriptome of endophthalmitis-
causing strains. The first aim will be tested by function analysis of recombinant HtrA variants cloned from the
viridans strains and by deletion mutagenesis of htrA from htrA-positive strains, as well as genetic addition of
htrA to htrA-negative strains. The second aim will employ whole genome sequencing of 21 strains followed by
bioinformatics pangenome analysis to identify conserved genes across the collection, and RNA-seq in vivo and
in vitro to determine the virulence transcriptome of this group of species. Accomplishment of these aims will
springboard the identification of key factors involved in ocular infection by these species. This research is
expected to benefit patient ocular health in the long-term because the knowledge to be gained can aid future
therapeutic development.

## Key facts

- **NIH application ID:** 10057004
- **Project number:** 1R21EY028325-01A1
- **Recipient organization:** UNIVERSITY OF MISSISSIPPI MED CTR
- **Principal Investigator:** MARY E MARQUART
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $193,750
- **Award type:** 1
- **Project period:** 2020-09-01 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10057004

## Citation

> US National Institutes of Health, RePORTER application 10057004, Characterization of viridans group streptococci from endophthalmitis (1R21EY028325-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10057004. Licensed CC0.

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