Authors: Mama Olouwafemi Mistourath, Gómez Paula, Ruiz-Ripa Laura, Gómez-Sanz Elena, Zarazaga Myriam, Torres Carmen
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Staphylococcal Carriage and Antimicrobial Resistance in Spanish Horses Researchers from Spain cultured nasal and faecal samples from 73 healthy horses at slaughter to characterise the frequency, diversity and resistance profiles of Staphylococcus species, with particular attention to methicillin-resistant strains and virulence determinants including leukocidins and exotoxins. Staphylococci were recovered from 90% of nasal samples and 66% of faecal samples, yielding 90 isolates across eight species; *Staphylococcus aureus* dominated (n=34), followed by *S. delphini* and *S. sciuri* (each n=19). All *S. aureus* isolates were methicillin-susceptible, with 82% showing full susceptibility to the antibiotics tested, whilst the remaining six isolates carried resistance genes to streptomycin, penicillin and trimethoprim-sulphamethoxazole; critically, the equine-adapted leukocidin gene *lukPQ* was present in all *S. aureus* strains except those of the newly documented ST1640 lineage (n=21), which itself predominated in the sample. The findings demonstrate that healthy horses represent a meaningful reservoir for virulent *S. aureus* with equine-specific virulence factors, and identify an emerging lineage (ST1640/t2559) in the equine population; although antibiotic resistance rates remain low overall, the prevalence of *lukPQ* warrants attention given its role in pathogenesis, and practitioners should consider staphylococcal carriage when assessing infection risk in wounds or post-operative complications.
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Practical Takeaways
- •Healthy horses are a significant reservoir for potentially virulent S. aureus strains; consider infection control measures during slaughter and processing to prevent human foodborne transmission
- •The majority of staphylococcal isolates show low antibiotic resistance, but awareness of resistance patterns is important for treatment decisions if clinical infections occur
- •S. aureus carriage is common in healthy horses without clinical signs; routine screening may not be necessary unless clinical mastitis or wound infections are present
Key Findings
- •Staphylococcus species detected in 90% of nasal samples and 66% of faecal samples from healthy slaughterhouse horses
- •S. aureus was the predominant species (n=34) with all isolates methicillin-susceptible; 28/34 were fully susceptible to all antibiotics tested
- •The lineage ST1640/t2559 was predominant (n=21) and is described for the first time in horses
- •The equine-adapted leukocidin gene lukPQ was present in all S. aureus isolates except ST1640 strains, indicating virulence potential