Enterococcus infections in foals.
Authors: Willis A T, Magdesian K G, Byrne B A, Edman J M
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Enterococcus infections in foals Over the past 30 years, enterococcal sepsis has become increasingly prevalent in foals, yet little has been documented about infection sites, antimicrobial resistance patterns, or clinical outcomes specific to this pathogen. Willis and colleagues retrospectively analysed 75 foals aged 0–30 days with enterococcal isolates and 170 control foals with other bacterial pathogens, examining culture sources, susceptibility profiles, and survival to discharge. The lower urogenital tract emerged as the predominant site of enterococcal infection, being 2.67 times more likely to yield Enterococcus than other bacteria, whilst enterococcal bacteraemia was significantly less common (odds ratio 0.17 compared to other pathogens). Alarmingly, nearly half of the enterococcal isolates demonstrated multiple antimicrobial resistance and multidrug resistance phenotypes (48% and 46% respectively), and foals with enterococcal infections had substantially poorer survival rates—only 50% survived to discharge compared with 63.5% of those with other bacterial aetiologies. For practitioners managing neonatal foal sepsis, these findings underscore the importance of obtaining urogenital cultures alongside blood cultures in at-risk individuals, and highlight that antimicrobial susceptibility testing should be prioritised when enterococci are isolated, given the high prevalence of resistance and the associated mortality risk.
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Practical Takeaways
- •Enterococcal infections in neonatal foals are increasing in prevalence and carry a worse prognosis than other bacterial sepsis; clinical suspicion should be high for urogenital infections in septic foals
- •Antimicrobial susceptibility testing is essential for enterococcal isolates as nearly half show multidrug resistance, which may explain poorer outcomes and guide treatment selection
- •Consider lower urogenital tract as a primary site of infection in foals with positive cultures, as enterococci show strong predilection for this location compared to other pathogens
Key Findings
- •Enterococcus was 2.67 times more likely to be isolated from the lower urogenital tract compared to other bacteria (P=0.0012)
- •Enterococci were significantly less likely to be isolated from blood cultures than other bacteria (OR 0.17, P<0.0001)
- •48% of Enterococcus isolates had a multiple antimicrobial resistance index ≥30% and 46% had a multidrug resistance index ≥30%
- •Foals with enterococcal infections had significantly lower survival to discharge (49.9% vs 63.5%, P=0.03)