Antimicrobial resistance in clinical bacterial isolates from horses in the UK.
Authors: Isgren Cajsa M, Williams Nicola J, Fletcher Owen D, Timofte Dorina, Newton Richard J, Maddox Thomas W, Clegg Peter D, Pinchbeck Gina L
Journal: Equine veterinary journal
Summary
# Antimicrobial Resistance in UK Equine Clinical Bacteria: Key Findings and Practice Implications Antimicrobial resistance (AMR) surveillance in horses is essential for informing empirical treatment protocols and identifying emerging resistance threats, yet UK-specific data remain limited. Researchers analysed 6,018 bacterial isolates from 4,038 diagnostic submissions across six major UK equine laboratories during 2018, examining resistance patterns across respiratory, urogenital, skin/wound, surgical site, and orthopaedic infections using standardised susceptibility testing. Multidrug resistance (MDR) was notably prevalent: E. coli showed 31.7% MDR, Staphylococcus spp. 25.3%, and over 25% in most isolates from surgical site/catheter-related/orthopaedic infections; alarmingly, 30.2% of Enterococcus submissions had no readily available adult equine treatment options in the UK. Referral hospitals reported significantly higher MDR rates than first-opinion practices for most pathogens, suggesting that complicated cases present amplified resistance challenges. For practitioners, these findings underscore the critical importance of culture-guided rather than empirical treatment selection—particularly for surgical and orthopaedic cases—and highlight the need for enhanced biosecurity protocols in hospital settings where resistance is concentrated.
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Practical Takeaways
- •High MDR rates in surgical, catheter, and orthopaedic infections mean empirical antibiotic selection should be conservative and guided by culture/susceptibility results; consider hospital biosecurity protocols to prevent MDR spread
- •When treating Enterococcus spp. infections, be aware that nearly one-third of isolates may have limited treatment options available in the UK, making early culture and susceptibility testing critical for treatment planning
- •Respiratory and urogenital infections show different resistance patterns than surgical infections, so tailor empirical therapy based on infection type and consider submitting samples for susceptibility testing to guide treatment decisions
Key Findings
- •Multidrug resistance (MDR) prevalence was 31.7% in E. coli, 25.3% in Staphylococcus spp., and >25% in most bacterial isolates from surgical/catheter/orthopaedic infections
- •30.2% of Enterococcus spp. positive submissions had no readily available treatment option for adult horses in the UK
- •MDR was significantly higher in referral hospital submissions compared to first opinion practice submissions for the majority of pathogens
- •6,018 bacterial isolates from 4,038 diagnostic submissions included respiratory (n=1,555), urogenital (n=1,010), and skin/wound (n=753) samples with varying resistance patterns by site