Infective Endocarditis: Oral Microbiome Correspondence With Blood Culture Bacterial Species
Objectives: Infective endocarditis (IE) is an uncommon disease with high morbidity and mortality rates. IE often develops from oral bacterial species that enter the systemic circulation. Our objective was to determine oral microbiome profiles of patients hospitalized with IE (N=9), patients at risk for IE (disease controls [DC]; N=28), and healthy controls (HC; N=37). We also sought to determine if there was a correspondence between oral species and species found in blood culture in same IE patient.
Methods: Oral samples (buccal mucosa [B], saliva [S], and tongue [T]) were collected from IE, DC, and HC groups. Subgingival plaque [Pb], supragingival plaque [Pp] were collected from IE and DC groups. Blood samples were collected from IE patients. Alpha and beta-diversities were determined for the sample site combinations BST (HC vs. DC, HC vs. IE, DC vs. IE), PbPp or Pb alone (DC vs. IE). LEfSe analysis and post hoc Mann-Whitney U-test were used to identify distinctive species (p<0.05). Distinctive species were subjected to ROC analysis. Bacterial species isolated from IE patients’ blood cultures were identified using 16S rRNA gene Sanger sequencing and BLASTn. A phylogram was created from a Multiple Sequence Comparison by Log-Expectation alignment.
Results: Alpha-diversity differences were significant in all comparisons except for HC vs. DC (p>0.05). All differences determined in beta-diversity comparisons were significant (p<0.05). LEfSe identified distinctive taxa in all comparisons. Each comparison, except HC vs. DC, had species ROC-curves with areas under the curve >0.90. Of 45 blood species isolates, 8 (17.8%) were identified as Staphylococcus aureus which was also identified in one matched saliva sample. Additionally, in one patient, Streptococcus mutans was identified in the supragingival and subgingival plaque and corresponding blood sample.
Conclusions: Significant oral microbiome changes occur in IE patients compared to patients at risk for IE and healthy controls. Further studies are needed to understand bacterial-host interactions associated with IE.