Oral microbiomes of patients with infective endocarditis (IE): a comparative pilot study of IE patients, patients at risk for IE and healthy controls.

Background: Infective endocarditis (IE) is an uncommon disease with high morbidity and mortality rates, which often develops from oral bacterial species entering circulation.

Objective: We compared oral microbiome profiles of three groups: IE patients (N  9 patients; n = 27 samples), disease controls at risk for IE (N = 28; n = 84), and healthy controls (N = 37; n = 111). Bacterial species in IE patients' blood cultures were identified for comparison with matched oral samples.

Design: Oral microbiome profiles were obtained from buccal mucosa, saliva, and tongue samples for all three groups and from sub- and supra-gingival plaque samples of the IE group (N = 9; n = 16) and disease controls (N = 28; n = 54). - and -diversities were determined based on relative abundance data. Discriminative species were identified by LEfSe, Mann-Whitney, and ROC analyses. Identity of the bacterial species in IE patients' blood cultures was confirmed by gene Sanger sequencing.

Results: - and -diversities differed between groups. Discriminative IE-associated species were identified, and . Two blood isolates were , also identified in one matched saliva sample. was present in one patient's plaque samples and blood culture.

Conclusions: Oral microbiomes of IE, non-IE disease controls, and healthy controls differed significantly. A better understanding of IE-related bacterial-host interactions is warranted.