Culture-independent and dependent evaluation of the equine paranasal sinus microbiota in health and disease.
Authors: Beste K J, Lawhon S D, Chamoun-Emanuelli A M, Duff A H, Coleman M C, Griffin C E, Hardy J, Whitfield-Cargile C M
Journal: Equine veterinary journal
Summary
# Editorial Summary The equine paranasal sinus microbiota remains poorly characterised despite frequent antimicrobial treatment of bacterial sinusitis, making it difficult for clinicians to distinguish pathogenic organisms from normal commensals when interpreting culture results. Using both culture-dependent methods and culture-independent 16S rRNA gene sequencing on sinus samples from healthy horses and those with clinical sinusitis, the researchers established a baseline microbial profile for healthy sinuses whilst identifying pathogenic shifts in diseased tissue. Key findings revealed that healthy sinuses harbour a diverse bacterial community dominated by Propionibacterium, Corynebacterium, and Staphylococcus species, with diseased sinuses showing significant alterations in microbial composition and reduced diversity; notably, some organisms commonly isolated from sinusitis cases were present in healthy sinuses, emphasising that culture results alone cannot determine pathogenicity. This work provides equine practitioners with essential reference data to interpret sinus cultures more reliably, potentially refining empirical antimicrobial selection and reducing unnecessary or inappropriate treatment in horses presenting with sinus disease. The findings underscore the importance of considering the sinus microbiota context when diagnosing bacterial sinusitis and support a move towards culture-guided rather than purely empirical therapy where feasible.
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Practical Takeaways
- •Culture results from equine sinus samples must be interpreted with knowledge of normal commensal flora to avoid treating colonizing organisms as pathogens
- •Understanding which organisms are part of normal sinus microbiota can improve antimicrobial stewardship and reduce unnecessary antibiotic use in sinusitis cases
- •This research provides evidence-based guidance for when sinus culture is truly indicated versus when empirical therapy based on typical pathogens is appropriate
Key Findings
- •Study compared culture-independent and culture-dependent methods to characterize the equine paranasal sinus microbiota in both healthy and diseased states
- •Results provide baseline data on which organisms constitute normal commensal microbiota of equine sinuses to better interpret culture results
- •Data helps guide empiric antimicrobial selection by distinguishing pathogenic bacteria from normal flora in sinusitis cases