Wild rodents and shrews are natural hosts of Staphylococcus aureus

Area of Science:

• Microbiology
• Veterinary Science
• Zoonotic Diseases

Background:

• Laboratory mice are crucial models for Staphylococcus aureus infection research.
• Previous studies revealed frequent S. aureus colonization in laboratory mice.
• Laboratory mice descend from wild house mice, prompting investigation into wild reservoirs.

Purpose of the Study:

• To determine if wild rodents and shrews are naturally colonized with S. aureus.
• To investigate potential host-specific adaptations of S. aureus in wild animals.
• To explore the role of wild animals as reservoirs and vectors for S. aureus.

Main Methods:

• Sampling of 295 wild animals across ten species in Germany, France, and the Czech Republic (2012-2015).
• Isolation and characterization of S. aureus from collected animal samples.
• Molecular typing of S. aureus isolates, including spa typing and lineage determination (clonal complex, sequence type).

Main Results:

• 15.3% (45/295) of wild animals were positive for S. aureus, yielding 48 isolates.
• Isolates belonged to ten spa types across six lineages, with CC49, CC1956, and ST890 being most prevalent.
• Wild S. aureus isolates lacked common human-associated virulence factors (e.g., immune evasion clusters, superantigen genes) and antibiotic resistance, indicating host adaptation.
• One isolate carried the mecC gene, suggesting a potential reservoir and vector role for methicillin-resistant S. aureus (MRSA).

Conclusions:

• Wild rodents and shrews are confirmed natural reservoirs for S. aureus.
• S. aureus isolates from wild animals exhibit characteristics suggesting long-term host adaptation.
• These findings highlight the ecological role of wild animals in S. aureus epidemiology and potential MRSA transmission.