Antimicrobial resistance in bacteria from horses: Epidemiology of antimicrobial resistance.
Authors: Maddox T W, Clegg P D, Williams N J, Pinchbeck G L
Journal: Equine veterinary journal
Summary
# Editorial Summary: Antimicrobial Resistance in Equine Bacteria Antimicrobial resistance represents an escalating clinical challenge in equine practice, yet the epidemiological landscape in horses remains poorly characterised compared to human medicine. Maddox and colleagues conducted a comprehensive literature review to map the prevalence, molecular characteristics and distribution of resistant bacteria in equine populations. Their findings revealed a concerning pattern: whilst community horses show low nasal carriage of methicillin-resistant *Staphylococcus aureus* (MRSA), hospitalised horses demonstrate significantly elevated prevalence, with molecular typing identifying both equine-associated strains and the zoonotic sequence type ST398. Extended-spectrum β-lactamase-producing and multidrug-resistant *Escherichia coli* have been documented in faecal carriage alongside resistant enterococci, *Salmonella*, *Acinetobacter* and *Pseudomonas* species, though characterisation of these latter organisms remains limited. The authors emphasise a critical gap in current knowledge: fundamental risk factor assessment and epidemiological understanding of resistance drivers in equine bacterial infections are substantially underdeveloped, creating an urgent need for longitudinal surveillance studies and treatment protocols that account for local resistance patterns in clinical decision-making.
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Practical Takeaways
- •Hospitalised horses carry substantially higher MRSA risk than community horses; implement appropriate infection control measures in equine hospitals
- •Antimicrobial resistance in equine pathogens is an emerging concern; prudent use of antimicrobials is essential to preserve treatment efficacy
- •Current knowledge gaps mean clinicians should consider resistance patterns when selecting antimicrobials and request culture/sensitivity testing rather than relying on empirical therapy
Key Findings
- •MRSA prevalence is low in community horses but significantly higher in hospitalised horses
- •Equine MRSA strains are predominantly horse-associated types or sequence type ST398
- •Multidrug-resistant and extended-spectrum β-lactamase-producing E. coli have been identified in horse faecal carriage
- •Limited epidemiological data exists on antimicrobial resistance in equine enterococci, Salmonella, Acinetobacter and Pseudomonas species