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Updated: May 11, 2026

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus
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Emergence of ST3390: A non-pigmented HA-MRSA clone with enhanced virulence

Emily A Felton1,2, Mary-Elizabeth Jobson1,2, Ariana M Virgillio3

  • 1Department of Molecules Biosciences, University of South Florida, Tampa, FL, USA.

Biorxiv : the Preprint Server for Biology
|April 1, 2025
PubMed
Abstract

Insights

This study investigates the rare MRSA ST3390 lineage, revealing its unique genomic traits and hypervirulent potential. The findings enhance understanding of MRSA (Methicillin-resistant Staphylococcus aureus) evolution and hospital-associated infections.

Area of Science:

  • Microbiology
  • Genomics
  • Epidemiology

Background:

  • CC5 is a successful hospital-associated lineage of Methicillin-resistant Staphylococcus aureus (MRSA).
  • CC5 strains exhibit widespread antibiotic resistance but cause less severe disease than community-associated MRSA.
  • Emerging CC5 descendant lineages globally display hypervirulent properties.

Purpose of the Study:

  • To genomically characterize the rare MRSA ST3390 lineage.
  • To investigate the epidemiology of ST3390 within Tampa General Hospital (TGH).
  • To assess the pathogenic capabilities of ST3390 using in vitro and in vivo models.

Main Methods:

  • Genomic analyses of ST3390 strains.
  • Epidemiological tracking of ST3390 at TGH.
  • In vitro and in vivo virulence assays.

Main Results:

  • ST3390 is rare globally but concentrated at TGH.
  • Unique SCCmec types and a TGH-specific spa-type cluster were identified.
  • ST3390 strains exhibit high cytotoxicity and hypervirulence in animal models, lacking staphyloxanthin pigment due to a CrtN deletion.

Conclusions:

  • This study provides the first characterization of ST3390 pathogenicity and genomics.
  • Findings deepen the understanding of CC5 clonal expansion.
  • The research illuminates MRSA diversification within patient populations.
Keywords:
MRSAStaphylococcus aureusmupirocin

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