Authors: de Lagarde Maud, Fairbrother John M, Arsenault Julie
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Antimicrobial resistance in equine populations remains poorly characterised in North America, despite escalating concerns about multidrug-resistant (MDR) pathogens in clinical settings. De Lagarde and colleagues examined faecal E. coli isolates from 225 healthy horses across 32 premises in Quebec, using both standard culture and selective enrichment with ceftriaxone to detect MDR and extended-spectrum β-lactamase (ESBL)/AmpC-producing strains, combined with PCR analysis to identify specific resistance genes. Nearly half of the horses (46.3%) shed MDR E. coli, with non-susceptibility most prevalent to ampicillin, amoxicillin/clavulanic acid and streptomycin; critically, 7.3% harboured ESBL/AmpC producers, predominantly blaCTX-M-1 genes but also blaCMY-2. Increased facility staffing and participation in equestrian events emerged as independent risk factors for MDR shedding, suggesting that human contact and horse movement between venues may facilitate dissemination of resistant bacteria through otherwise healthy populations. These findings highlight that subclinical carriage of resistant E. coli is far more prevalent than many practitioners may appreciate, and the identified epidemiological risk factors offer practical targets—such as biosecurity protocols and limiting unnecessary movement—for developing preventative guidelines within equine facilities and competitions.
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Practical Takeaways
- •Nearly half of healthy horses carry multidrug-resistant bacteria in their gut; implement enhanced biosecurity protocols, particularly around staff numbers and event participation, to reduce spread within facilities
- •Equestrian event participation is a significant risk factor for MDR E. coli shedding—establish hygiene practices and consider screening protocols before attending competitions or moving horses between premises
- •The high prevalence of resistant gram-negative bacteria warrants judicious antibiotic use and culture-guided therapy in equine practice; reserve β-lactam antibiotics and monitor treatment response carefully
Key Findings
- •46.3% of healthy horses in Quebec shed multidrug-resistant E. coli in feces
- •7.3% of horses harbored ESBL/AmpC-producing E. coli, with blaCTX-M-1 as the most common gene identified
- •Non-susceptibility was most common to ampicillin, amoxicillin/clavulanic acid, and streptomycin
- •Number of staff and equestrian event participation were identified as risk factors for shedding MDR isolates