# Modeling the Emergence of MRSA Strains

> **NIH NIH R21** · UNIVERSITY OF MISSISSIPPI MED CTR · 2021 · $271,250

## Abstract

ABSTRACT
 Methicillin-resistant Staphylococcus aureus (MRSA) causes healthcare- and community-
associated infections that are among the leading causes of death due to antibiotic-resistant
bacteria in the US. Most MRSA infections in the US over the past 20 years have been caused by
two ecologically successful strains. Although we have extensive knowledge about how MRSA
strains are transmitted, we still lack a basic understanding of the emergence process by which
strains spread from their origin to achieve their current geographic distribution, genetic diversity,
and fitness. Here, we propose to explore and develop a population genetics model of MRSA strain
emergence. Our hypothesis is that the origin and spread of MRSA strains can be accurately
modeled as a geographic range expansion with a strong serial founder effect. We will test this
hypothesis with two Specific Aims. Aim 1 will characterize the extent to which a range expansion
model explains the population genetics of the two predominant MRSA strains in the US, by
sequencing and analyzing bacterial genomes from a geographically diverse isolate collection and
by modeling the data with Approximate Bayesian Computation. Aim 2 will characterize the fitness
consequences of range expansion and the prediction of fitness from genome sequences, by using
an innovative assay of MRSA growth on a surface and by calculating a novel genomic score that
can accurately predict the surface fitness of individual isolates. The discovery of geographic
gradients underlying the genetic diversity and fitness of MRSA strains, as predicted by this model,
could revolutionize our understanding of strain emergence and change how we interact with
geographically different populations of a strain. This understanding ultimately may be essential
for controlling and predicting the emergence of new strains.

## Key facts

- **NIH application ID:** 10303444
- **Project number:** 1R21AI156661-01A1
- **Recipient organization:** UNIVERSITY OF MISSISSIPPI MED CTR
- **Principal Investigator:** David Ashley Robinson
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $271,250
- **Award type:** 1
- **Project period:** 2021-08-19 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10303444

## Citation

> US National Institutes of Health, RePORTER application 10303444, Modeling the Emergence of MRSA Strains (1R21AI156661-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10303444. Licensed CC0.

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