Increased occurrence of Staphylococcus aureus in wild ungulates intended for human consumption – An update on the monitoring in Brandenburg, Germany

Monitoring data on <i>Staphylococcus</i> (<i>S</i>.) <i>aureus</i> in wild animals are scarce, yet transmission to humans and livestock remains a concern. <i>S. aureus</i> can cause infections in humans and animals, and the production of staphylococcal enterotoxins (SEs) may cause food poisoning. This study monitored the occurrence of <i>S. aureus</i> in wild ungulates intended for human consumption in Brandenburg, Germany. A total of 323 nasal swabs were collected from wild boar, roe, fallow, and red deer during the 2023/24 hunting season. Samples were analyzed by selective enrichment. Isolates were identified using MALDI-TOF MS. Whole-genome sequencing was used for analyses of genotypes, antimicrobial resistance (AMR) and virulence genes as well as phylogeny. Phenotypic AMR was also determined. <i>S. aureus</i> was recovered from 58 swabs (18 %), exceeding the occurrence in 2021/22 (8 %) by over twofold. Fallow deer showed the highest detection rate (39 %), followed by red deer (32 %), roe deer (16 %), and wild boar (10 %). <i>S. aureus</i> isolates represented diverse sequence types (STs), with a majority of ST1, ST133 and ST425. Some isolates showed high clonality, despite originating from different hosts. Genes encoding SE or SE-like (SEl) proteins were found in 26 isolates and the toxic shock syndrome toxin encoding <i>tsst</i>-1 gene in one. AMR gene carriage was low, though one isolate carried resistance genes to beta-lactams, macrolides, and aminoglycosides. Wild ungulates may carry enterotoxigenic <i>S. aureus</i>. Foodborne illness can be prevented by hygiene and temperature control during processing and storage of game meat, while safe carcass handling can reduce the risk of infection.