The relationship between tooth extraction and changes in blood microbiome in horses

Abstract

Bacteremia resulting from dental surgery is increasingly recognized as a health risk, especially in older and immunocompromised patients (in human medicine and also now in equine veterinary medicine). Dentistry-associated bacteremia can lead to remote infections, as exemplified by valvular endocarditis. Emerging evidence points to a novel role played by oral cavity commensals in the pathogenesis of diabetes, respiratory disease, cardiovascular disease, and adverse pregnancy outcomes. Whether dental extraction, a commonly undertaken procedure in old horses, causes bacteremia has not been reported extensively. In a prospective clinical study using next generation sequencing (based on bacterial 16S rRNA), the circulating blood microbiome was characterized before and at 1 hour following extraction of incisor, canine or cheek teeth from 29 adult horses with dental disease. 16S rRNA gene sequencing results from the blood microbiome were compared with those from gingival swab samples obtained prior to extraction at the location of the diseased tooth. Univariate data were first tested for normality using the Shapiro-Wilk method. Non-normally distributed data were then tested using a Kruskal-Wallis analysis of variance (ANOVA) on ranks, followed by post hoc pairwise comparisons using Dunn's method, with significance defined by p < 0.05. Multivariate data were compared using permutational multivariate ANOVA (PERMANOVA) based on Jaccard similarities, using Past3 software. Bacteremia associated with translocated gingival commensals was demonstrated in horses undergoing exodontia and was, in some cases, still evident one hour post-operatively.