Emergence of ST3390: A Novel Apigmented MRSA Clone From the CC5 Lineage.

Authors

• Emily A Felton
• Mary-Elizabeth Jobson
• Nathanial J Torres
• Rachel M Washburn
• Ariana Virgillio, Lehigh Valley Health NetworkFollow
• Joshua Alvior
• Eleonora Cella
• Amorce Lima
• Deanna Becker
• Suzane Silbert
• Taj Azarian
• Kami Kim
• Lindsey N Shaw

Publication/Presentation Date

1-17-2026

Abstract

BACKGROUND: One of the most successful and widely-distributed hospital-associated lineages of MRSA is clonal complex 5 (CC5). These strains are known for widespread antibiotic resistance but less severe disease than CA-MRSA counterparts. Recently, CC5 descendant lineages have appeared globally with hypervirulent properties. Herein, we identify and characterize a rare and novel CC5 MRSA sequence type, ST3390.

METHODS: We used whole genome sequencing, alongside phenotypic characterizations, genetic complementation, blood viability- and neutrophil-killing assays, and a murine model of sepsis to study the pathogenic capabilities of ST3390 strains.

RESULTS: To date, there have only been 65 recorded instances of infection caused by ST3390 globally, with 36 of those occurring in Tampa (TPA-ST3390). Genomic analysis of strains identified numerous spa-types, with a t010 cluster found only in our strains. Exploration of AMR genes detected the presence of unique hybrid SCCmec types, with ∼90% of Tampa strains possessing components of SCCmecIa, SCCmecIIa, and/or SCCmecVIII. Phenotypically, all ST3390 strains lack the staphyloxanthin pigment, which is mediated by a conserved 6aa in frame deletion within the staphyloxanthin biosynthesis protein CrtN. TPA-ST3390 strains display high levels of cytotoxicity towards human neutrophils compared with other CC5 lineages and are also virulent in animal models of infection.

CONCLUSIONS: This is the first study to characterize the pathogenicity and genomic architecture of the rare MRSA lineage ST3390. Our work provides a deeper understanding of the clonal expansion of CC5, and the wider diversification of Staphylococcus aureus isolates within patient populations.

Volume

233

Issue

1

First Page

27

Last Page

37

ISSN

1537-6613

Published In/Presented At

Felton, E. A., Jobson, M. E., Torres, N. J., Washburn, R. M., Virgillio, A. M., Alvior, J., Cella, E., Lima, A., Becker, D., Silbert, S., Azarian, T., Kim, K., & Shaw, L. N. (2026). Emergence of ST3390: A Novel Apigmented MRSA Clone From the CC5 Lineage. The Journal of infectious diseases, 233(1), 27–37. https://doi.org/10.1093/infdis/jiaf410

Disciplines

Medical Education | Medicine and Health Sciences

PubMedID

40795157

Department(s)

USF-LVHN SELECT Program, USF-LVHN SELECT Program Students

Document Type

Article