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Virulence Phenotypes Differentiate Persistent vs. Resolving Isolates of Human Staphylococcus aureus Bacteremia
Liana C Chan1,2,3,4, Hong K Lee1,4, Ling Wang1,4
1Harbor-UCLA Medical Center, Division of Molecular Medicine, Torrance, CA 90502, USA.
Antibiotics (Basel, Switzerland)
|April 27, 2026
Summary
Persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (SAB) involves bacterial adaptations that evade treatment. Understanding these virulence differences is key to developing new strategies against persistent SAB.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Staphylococcus aureus bacteremia (SAB) is a severe bloodstream infection.
- Methicillin-resistant SA (MRSA) causes up to 35% of SAB treatment failures.
- Persistent SAB may involve small colony variant (SCV) adaptation.
Purpose of the Study:
- To compare virulence phenotypes and mechanisms of persistent (PB) versus resolving (RB) MRSA isolates from SAB.
- To investigate MRSA adaptations contributing to treatment persistence.
Main Methods:
- Assessed virulence phenotypes (hemolysis, biofilm, proteolysis) in PB vs. RB MRSA isolates.
- Analyzed human endothelial cell invasion and intracellular SCV formation.
- Examined isolate susceptibility to host defense peptides (HDPs) under varying pH and antibiotic conditions.
Main Results:
- PB isolates showed reduced hemolysis and biofilm formation compared to RB isolates.
- Intracellular SCV formation was more frequent in PB isolates, correlating inversely with pH.
- Distinct HDP susceptibilities and mechanistic signatures were observed between PB and RB isolates.
Conclusions:
- MRSA isolates from persistent SAB exhibit differential virulence profiles suggesting immune subversion.
- Understanding MRSA adaptations is crucial for developing novel therapies against persistent SAB.
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