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Updated: Feb 5, 2026
Development and Assessment of Intracellular Infection Models for Staphylococcus aureus
Published on: January 17, 2025
Staphylococcus pseudintermedius Surface Protein L (SpsL) Is Required for Abscess Formation in a Murine Model of
Amy C Richards1, Marie O'Shea1, Philippa M Beard1
1The Roslin Institute, Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Abstract:
Staphylococcus pseudintermedius is the leading cause of pyoderma in dogs and is often associated with recurrent skin infections that require prolonged antibiotic therapy. High levels of antibiotic use have led to multidrug resistance, including the emergence of epidemic methicillin-resistant clones. Our understanding of the pathogenesis of S. pseudintermedius skin infection is very limited, and the identification of the key host-pathogen interactions underpinning infection could lead to the design of novel therapeutic or vaccine-based approaches for controlling disease. Here, we employ a novel murine cutaneous-infection model of S. pseudintermedius and investigate the role of the two cell wall-associated proteins (SpsD and SpsL) in skin disease pathogenesis. Experimental infection with wild-type S. pseudintermedius strain ED99 or a gene-deletion derivative deficient in expression of SpsD led to a focal accumulation of neutrophils and necrotic debris in the dermis and deeper tissues of the skin characteristic of a classical cutaneous abscess. In contrast, mice infected with mutants deficient in SpsL or both SpsD and SpsL developed larger cutaneous lesions with distinct histopathological features of regionally extensive cellulitis rather than focal abscessation. Furthermore, comparison of the bacterial loads in S. pseudintermedius-induced cutaneous lesions revealed a significantly increased burden of bacteria in the mice infected with SpsL-deficient mutants. These findings reveal a key role for SpsL in murine skin abscess formation and highlight a novel function for a bacterial surface protein in determining the clinical outcome and pathology of infection caused by a major canine pathogen.
Insights
Staphylococcus pseudintermedius causes canine pyoderma, leading to antibiotic resistance. This study reveals the SpsL protein is crucial for abscess formation in mice, offering new therapeutic targets for canine skin infections.
Area of Science:
- Veterinary Dermatology
- Bacterial Pathogenesis
- Host-Pathogen Interactions
Background:
- Staphylococcus pseudintermedius is a primary cause of canine pyoderma, frequently leading to recurrent skin infections and extensive antibiotic use.
- The rise of multidrug-resistant strains, including methicillin-resistant Staphylococcus pseudintermedius, necessitates a deeper understanding of infection mechanisms.
- Limited knowledge of S. pseudintermedius pathogenesis hinders the development of novel treatments and vaccines.
Purpose of the Study:
- To investigate the roles of two cell wall-associated proteins, SpsD and SpsL, in the pathogenesis of S. pseudintermedius skin infections.
- To elucidate the host-pathogen interactions critical for disease development.
- To identify potential targets for new therapeutic or vaccine strategies.
Main Methods:
- Development and utilization of a novel murine cutaneous infection model for S. pseudintermedius.
- Experimental infections using wild-type S. pseudintermedius and gene-deletion mutants lacking SpsD, SpsL, or both.
- Histopathological analysis of skin lesions to characterize inflammation and tissue damage.
- Quantification of bacterial loads within infected tissues.
Main Results:
- Infection with wild-type or SpsD-deficient S. pseudintermedius resulted in focal cutaneous abscesses.
- Mutants deficient in SpsL, or both SpsD and SpsL, induced larger lesions with features of cellulitis rather than abscesses.
- A significantly higher bacterial burden was observed in lesions infected with SpsL-deficient mutants compared to wild-type.
Conclusions:
- The bacterial surface protein SpsL plays a critical role in the formation of skin abscesses caused by S. pseudintermedius in a murine model.
- SpsL influences the clinical outcome and pathology of S. pseudintermedius skin infections.
- These findings provide insights into host-pathogen interactions and suggest SpsL as a potential target for controlling canine pyoderma.
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