Laboratory mice are the most commonly used animal model for Staphylococcus aureus infection studies. We have previously shown that laboratory mice from global vendors are frequently colonized with S. aureus. Laboratory mice originate from wild house mice. Hence, we investigated whether wild rodents, including house mice, as well as shrews are naturally colonized with S. aureus and whether S. aureus adapts to the wild animal host. 295 animals of ten different species were caught in different locations over four years (2012-2015) in Germany, France and the Czech Republic. 45 animals were positive for S. aureus (15.3%). Three animals were co-colonized with two different isolates, resulting in 48 S. aureus isolates in total. Positive animals were found in Germany and the Czech Republic in each studied year. The S. aureus isolates belonged to ten different spa types, which grouped into six lineages (clonal complex (CC) 49, CC88, CC130, CC1956, sequence type (ST) 890, ST3033). CC49 isolates were most abundant (17/48, 35.4%), followed by CC1956 (14/48, 29.2%) and ST890 (9/48, 18.8%). The wild animal isolates lacked certain properties that are common among human isolates, e.g., a phage-encoded immune evasion cluster, superantigen genes on mobile genetic elements and antibiotic resistance genes, which suggests long-term adaptation to the wild animal host. One CC130 isolate contained the mecC gene, implying wild rodents might be both reservoir and vector for methicillin-resistant . In conclusion, we demonstrated that wild rodents and shrews are naturally colonized with S. aureus, and that those S. aureus isolates show signs of host adaptation.

Department of Forest Ecology Mendel University in Brno Zemědělská 3 61300 Brno Czech Republic

Department of Immunology University Medicine Greifswald Sauerbruchstraße DZ7 17475 Greifswald Germany

Department of Zoology Fisheries Hydrobiology and Apiculture Faculty of Agronomy Mendel University in Brno Zemědělská 1 61300 Brno Czech Republic

Institut Claude Bourgelat Laboratoire de Toxicologie BIOLYTICS 1 Avenue Bourgelat 69280 Marcy l'Étoile France

Institute for Plant Protection in Horticulture and Forests Vertebrate Research Julius Kühn Institute Federal Research Centre for Cultivated Plants Toppheideweg 88 48161 Münster Germany

Institute of Microbiology and Epizootics Veterinary Faculty Freie Universität Berlin Robert von Ostertag Straße 7 13 14163 Berlin Germany

Institute of Novel and Emerging Infectious Diseases Friedrich Loeffler Institut Federal Research Institute for Animal Health Südufer 10 17493 Greifswald Insel Riems Germany

National Reference Centre for Staphylococci and Enterococci Division Nosocomial Pathogens and Antibiotic Resistances Department of Infectious Diseases Robert Koch Institut Burgstraße 37 38855 Wernigerode Germany

References provided by Crossref.org

Molecular Epidemiology of Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in Wild, Captive and Laboratory Rats: Effect of Habitat on the Nasal S. aureus Population