Cross-sectional study of antimicrobial-resistant bacteria in horses. Part 1: Prevalence of antimicrobial-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus.
Authors: Maddox T W, Clegg P D, Diggle P J, Wedley A L, Dawson S, Pinchbeck G L, Williams N J
Journal: Equine veterinary journal
Summary
# Editorial Summary Antimicrobial resistance in equine pathogens poses a growing public health concern, yet baseline prevalence data for UK horses had remained sparse until this investigation. Researchers recruited 692 horses across 525 premises via 65 randomly selected veterinary practices, collecting nasal swabs and faecal samples to quantify carriage of methicillin-resistant *Staphylococcus aureus* (MRSA) and resistant *Escherichia coli*, with multilevel logistic regression accounting for clustering effects and spatial variation across regions. Whilst MRSA nasal carriage proved uncommon at just 0.6% prevalence, faecal carriage of antimicrobial-resistant *E. coli* was markedly prevalent at 69.5%, with 6.3% producing extended-spectrum β-lactamases (ESBL)—clinically significant producers of broad-spectrum resistance. The study revealed considerable geographical variation in resistance patterns, suggesting regional differences in antimicrobial use or biosecurity practices warrant investigation. These findings highlight that farriers, veterinarians and equine professionals should view the widespread intestinal carriage of resistant *E. coli* as a reservoir concern, both for individual horse health during infection and as a potential source of resistance transmission, making prudent antimicrobial stewardship and enhanced hygiene protocols increasingly important in equine practice.
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Practical Takeaways
- •Antimicrobial-resistant E. coli is highly prevalent in UK horses; consider resistance patterns when treating gastrointestinal infections and implement prudent antibiotic use protocols
- •MRSA carriage in horses is rare, so routine screening is not warranted, but awareness remains important for zoonotic risk management and infection control in equine facilities
- •Geographic variation in resistance patterns suggests practitioners should be aware of local resistance epidemiology when selecting empirical antimicrobial therapy
Key Findings
- •Faecal carriage of antimicrobial-resistant E. coli was prevalent at 69.5% (95% CI 65.9-73.1%) in UK horses
- •Extended-spectrum β-lactamase-producing E. coli was detected in 6.3% (95% CI 4.1-9.6%) of horses
- •Nasal carriage of MRSA was rare at 0.6% (95% CI 0.2-1.5%) in the UK equine community
- •Significant spatial variation in risk of antimicrobial-resistant and multidrug-resistant E. coli carriage was identified across the UK