Large Animal
Scientific Abstracts
Information regarding the microbiome in sinusitis using genetic sequencing is lacking and more-in-depth understanding of the microbiome could improve antimicrobial selection and treatment outcomes. Objectives of this study were to describe the sinus microbiota in samples from horses with sinusitis and compare microbiota and the presence of antimicrobial resistance genes between primary, dental-related, and other secondary causes of sinusitis. Records of equine sinusitis from 2017-2021 were reviewed and historical microbial amplicon sequence data were obtained from clinical diagnostic testing of sinus secretions. Following bioinformatic processing of bacterial and fungal sequence data, the sinus microbiota was investigated from the perspectives of bacterial alpha and beta diversity, and differentially abundant taxa. Quantitative PCR further allowed for comparisons of estimated bacterial abundance and detection rate of common antibiotic resistance-associated genes. Of 81 samples analyzed from 70 horses, bacterial microbiome was characterized in 66, and fungal in five. Only sinusitis etiology was shown to significantly influence microbiome diversity and composition (p < 0.05). Dental sinusitis (n=44) was associated with a significantly higher proportion of obligate anaerobic bacteria, whereas primary sinusitis (n=12) and other (n=10) diagnoses were associated with fewer bacteria and higher proportions of facultative anaerobic and aerobic genera. Antimicrobial resistance genes and fungal components were exclusively identified in dental-related sinusitis. Limitations include the retrospective nature, small sample size, and incomplete prior antimicrobial administration data. Molecular characterization in sinusitis identifies microbial species which may be difficult to isolate via culture, and microbiome profiling can differentiate sinusitis etiology, which may inform antimicrobial therapy.