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Updated: Nov 17, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
A Murine Skin Infection Model Capable of Differentiating the Dermatopathology of Community-Associated MRSA Strain
Jack Zhang1,2, John Conly1,2,3,4,5, JoAnn McClure1,4
1Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB T2N4N1, Canada.
Abstract:
USA300 is a predominant and highly virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain that is a leading cause of skin and soft tissue infections. We established a murine intradermal infection model capable of demonstrating dermatopathological differences between USA300 and other MRSA strains. In this model, USA300 induced dermonecrosis, uniformly presenting as extensive open lesions with a histologically documented profound inflammatory cell infiltrate extending below the subcutis. In contrast, USA400 and a colonizing control strain M92 caused only localized non-ulcerated skin infections associated with a mild focal inflammatory infiltrate. It was also determined that the dermonecrosis induced by USA300 was associated with significantly increased neutrophil recruitment, inhibition of an antibacterial response, and increased production of cytokines/chemokines associated with disease severity. These results suggest that induction of severe skin lesions by USA300 is related to over-activation of neutrophils, inhibition of host antibacterial responses, and selective alteration of host cytokine/chemokine profiles.
Insights
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) USA300 causes severe skin infections. A new mouse model shows USA300 induces extensive dermonecrosis by over-activating neutrophils and altering host responses.
Area of Science:
- Microbiology
- Dermatology
- Immunology
Background:
- USA300 is a prevalent and virulent community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain.
- This strain is a primary cause of skin and soft tissue infections.
Purpose of the Study:
- To establish a murine intradermal infection model to differentiate USA300's dermatopathology from other MRSA strains.
- To investigate the mechanisms underlying USA300-induced dermonecrosis.
Main Methods:
- Development of a murine intradermal infection model.
- Histopathological analysis of skin lesions.
- Assessment of inflammatory cell infiltrate, neutrophil recruitment, and cytokine/chemokine production.
Main Results:
- USA300 induced extensive dermonecrosis with deep inflammatory infiltrate, unlike USA400 and M92 strains.
- USA300 infection showed significantly increased neutrophil recruitment.
- Inhibition of host antibacterial response and elevated pro-inflammatory cytokines/chemokines were observed with USA300.
Conclusions:
- USA300's severe skin lesions are linked to neutrophil over-activation.
- Inhibition of host antibacterial responses and altered cytokine profiles contribute to USA300 virulence.
- The murine model effectively distinguishes pathogenic differences among MRSA strains.
