Temporal trends in prevalence of bacteria isolated from foals with sepsis: 1979-2010.
Authors: Theelen M J P, Wilson W D, Edman J M, Magdesian K G, Kass P H
Journal: Equine veterinary journal
Summary
Over a 31-year period (1979–2010), researchers at UC Davis reviewed culture results from neonatal foals (≤30 days old) diagnosed with sepsis, tracking how the bacterial pathogens involved have shifted over time. Using retrospective medical records and conventional microbiological identification methods on 291 bacterial isolates from blood or internal organ cultures, the team employed statistical trend analysis to detect significant changes in prevalence patterns. Gram-positive bacteria increased substantially across the decades, whilst Enterobacteriaceae—historically the most prevalent sepsis pathogens—declined significantly; notably, Enterococcus species appeared with increasing frequency in recent years. Although Gram-negative organisms remain the primary isolates in neonatal foal sepsis, this epidemiological drift towards Gram-positive bacteria has important implications: practitioners must continue empirical antimicrobial protocols covering both spectra whilst awaiting culture and susceptibility results, and the rising Enterococcus prevalence warrants particular caution owing to these organisms' unpredictable antimicrobial resistance patterns and capacity to transfer resistance genes horizontally. These temporal trends suggest that static antibiotic protocols developed decades ago may no longer reflect current pathogenic landscapes in neonatal foal populations, necessitating periodic reassessment of empirical treatment guidelines.
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Practical Takeaways
- •Initial antimicrobial therapy for septic foals should cover both Gram-positive and Gram-negative bacteria while awaiting culture and susceptibility results, reflecting the changing prevalence patterns over time
- •Be aware that Enterococcus spp. susceptibility patterns are unpredictable and these organisms can transfer antimicrobial resistance genes to other pathogens, complicating treatment decisions
- •Individualize antibiotic selection based on local epidemiological trends and regional resistance patterns rather than relying on older published protocols
Key Findings
- •Gram-positive bacterial isolates increased significantly from 1979 to 2010 in foals with sepsis
- •Enterobacteriaceae prevalence, particularly Klebsiella spp., decreased over the 31-year study period
- •Enterococcus spp. isolates were cultured more frequently in recent years
- •Gram-negative bacteria remain the most common isolates despite increasing prevalence of Gram-positive bacteria