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Updated: May 29, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Emergence of MRSA ST612 in horses and of MSSA CC398 in cats in France
Marisa Haenni1, Séverine Murri1, Antoine Drapeau1
1Unité Antibiorésistance et Virulence Bactériennes, ANSES-Université de Lyon, Lyon, France.
Objectives:
Staphylococcus aureus is an important zoonotic pathogen that has often been seen in animals through the prism of the MRSA clonal complex (CC) 398 in pigs and in-contact humans. The goal of this study was first to assess the prevalence of MRSA, and second to look for MSSA CC398 in cats, dogs and horses in France.
Methods:
Clinical S. aureus isolates (n = 479) were collected from 186 cats, 143 dogs and 150 horses during 2022-2023 all over the French territory. Antibiograms were performed on all isolates. MRSA and MSSA CC398 isolates were subject to WGS. Core genome (cg) MLST-based and SNP-based phylogenetic analyses were performed using published methodologies, and characterization of the isolates was performed using publicly available tools.
Results:
Sixty-six MRSA isolates were identified in 14 cats (7.5%), 9 dogs (6.3%) and 43 horses (28.7%). The epidemiology of MRSA in cats and dogs remained stable since a previous study in 2015, with the presence of both CC398 and human-associated clones. In horses, in contrast, an important increase in MRSA (from 10% to 28.7%) was observed, potentially attributable to the emergence of the ST612 clones. In parallel, CC398 MSSA, a clone usually described as animal-independent, was found in 24.2% of the cat isolates.
Conclusions:
Our study, which is leading the way to a genomic surveillance of S. aureus in France, revealed the emergence of both MRSA ST612 in horses and MSSA CC398 in cats. These clones should be closely monitored to avoid their zoonotic spread and to understand their dynamics of transmission between humans and animals.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) ST612 emerged in French horses, while methicillin-susceptible Staphylococcus aureus (MSSA) CC398 was found in cats. These findings highlight the need for genomic surveillance of S. aureus to prevent zoonotic spread.
Area of Science:
- Veterinary Microbiology
- Zoonotic Disease Surveillance
- Genomic Epidemiology
Background:
- Staphylococcus aureus is a significant zoonotic pathogen, with MRSA clonal complex (CC) 398 frequently identified in pigs and associated humans.
- Understanding the prevalence and dynamics of S. aureus, including MRSA and MSSA CC398, in companion animals and horses is crucial for public health.
Purpose of the Study:
- To determine the prevalence of MRSA in cats, dogs, and horses in France.
- To investigate the presence of MSSA CC398 in these animal populations.
- To establish a baseline for genomic surveillance of S. aureus in French animals.
Main Methods:
- Collection of 479 clinical S. aureus isolates from cats, dogs, and horses across France (2022-2023).
- Antibiogram testing for all isolates.
- Whole Genome Sequencing (WGS) for MRSA and MSSA CC398 isolates.
- Core genome (cg) MLST and SNP-based phylogenetic analyses.
Main Results:
- MRSA was detected in 14.2% of isolates (7.5% cats, 6.3% dogs, 28.7% horses).
- MRSA prevalence in horses significantly increased to 28.7%, with ST612 clones emerging.
- MSSA CC398 was identified in 24.2% of cat isolates.
Conclusions:
- The study identified the emergence of MRSA ST612 in horses and MSSA CC398 in cats in France.
- These emerging clones require close monitoring to prevent zoonotic transmission and understand human-animal transmission dynamics.
- Genomic surveillance is essential for tracking S. aureus evolution and spread in animal populations.
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