Antibiograms of Bacterial Cultures From Equine Neonates at a United Kingdom Hospital: 381 Samples (2018-2023).
Authors: Graham Annabelle E, Colgate Victoria A, Floyd Emily F
Journal: Journal of veterinary internal medicine
Summary
# Antibiograms of Bacterial Cultures From Equine Neonates at a UK Hospital Between 2018 and 2023, researchers at Rossdales Equine Hospital retrospectively analysed 381 bacterial samples from blood and synovial fluid collected from 208 foals aged 30 days or younger, using disc diffusion susceptibility testing to establish locally relevant antibiotic resistance patterns. Gram-positive bacteria dominated the isolates (75%), with Enterococcus species being most prevalent at 26% of all positive cultures; notably, multidrug resistance was identified in 21% of isolates, with Enterococcus accounting for over one-third of these resistant strains. The combination of ampicillin and amikacin demonstrated in vitro susceptibility against 90% of aerobic isolates, supporting its continued use as empirical first-line therapy for septic foals in this population, though the unpredictable and frequently resistant nature of Enterococcus warrants culture and susceptibility-guided adjustments. Interestingly, neither the presence of positive bacterial cultures nor multidrug-resistant isolates significantly impacted foal survival (87% discharge rate), suggesting that appropriate antimicrobial selection and supportive care remain effective despite challenging pathogens. For UK practitioners managing neonatal sepsis, these findings reinforce the importance of obtaining cultures before empirical therapy and maintaining awareness of local resistance patterns—particularly the high prevalence of resistant Enterococcus—rather than assuming broad-spectrum coverage will override the need for targeted, susceptibility-guided treatment decisions.
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Practical Takeaways
- •Ampicillin and amikacin combination therapy is empirically appropriate for neonatal foal infections in UK hospitals, providing coverage against 90% of aerobic bacteria encountered
- •Culture and susceptibility testing remains critical given unpredictable Enterococcus susceptibility patterns and high frequency of MDR Enterococcus isolates
- •Geographic antibiogram data from your specific region/facility should guide empirical antimicrobial selection, as resistance patterns vary by location
Key Findings
- •Gram-positive bacteria predominated (75% of 91 isolates), with Enterococcus being the most common (26%)
- •Multidrug resistance identified in 21% of isolates, with Enterococcus accounting for 7 of 19 MDR cases
- •Ampicillin and amikacin combination showed in vitro susceptibility in 90% of aerobic isolates
- •87% of foals were successfully discharged; no significant association between positive culture/MDR isolates and survival outcomes