Equine sinusitis aetiology is linked to sinus microbiome by amplicon sequencing.
Authors: Lowman Megan E, Tipton Craig D, Labordère Alexandra L, Brown James A
Journal: Equine veterinary journal
Summary
# Equine Sinusitis Aetiology Linked to Sinus Microbiome Amplicon sequencing of 81 sinus samples from 70 horses revealed that the microbial composition and diversity of equine sinusitis differs markedly depending on underlying cause, with significant implications for antimicrobial selection and treatment strategy. Dental-related sinusitis (44 cases) demonstrated a distinctly different microbiota profile—dominated by obligate anaerobic bacteria with detectable antimicrobial resistance genes and fungal components—whilst primary sinusitis (12 cases) and other secondary causes (10 cases) were characterised by lower bacterial diversity and higher proportions of facultative anaerobic and aerobic species. Only sinusitis aetiology proved statistically significant (p < 0.05) in influencing microbiome diversity and composition across the dataset, suggesting that diagnostic categorisation of the underlying cause is the strongest predictor of which organisms will be present. For practitioners, this molecular profiling approach can identify fastidious organisms that standard culture techniques often fail to recover, enabling more targeted antimicrobial therapy rather than empirical broad-spectrum treatment. The findings underline the importance of thorough diagnostic investigation to establish whether sinusitis is primary, dental-related or secondary to another condition, as this determination fundamentally shapes the expected microbial landscape and therefore rational treatment selection.
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Practical Takeaways
- •Microbiome analysis can help identify the underlying cause of sinusitis (primary vs. dental-related), guiding targeted antimicrobial therapy selection and improving treatment outcomes
- •Dental-related sinusitis cases require antimicrobial agents effective against obligate anaerobic bacteria and may involve resistance genes, whereas primary sinusitis may respond to agents targeting facultative anaerobes and aerobes
- •Genetic sequencing of sinus secretions reveals pathogens that culture-based diagnostics may miss, enabling more comprehensive and accurate diagnosis
Key Findings
- •Sinusitis aetiology was the only significant factor influencing microbiome diversity and composition (p<0.05)
- •Dental-related sinusitis (n=44) was associated with significantly higher proportions of obligate anaerobic bacteria, while primary sinusitis (n=12) and other causes (n=10) had fewer bacteria with higher proportions of facultative and aerobic genera
- •Antimicrobial resistance genes and fungal components were exclusively identified in dental-related sinusitis cases
- •Microbiome profiling successfully differentiated sinusitis aetiology and identified microbial species difficult to isolate via culture