Invasion of Human Coronary Artery Endothelial Cells by Streptococcus mutans

Introduction: Dissemination of oral bacteria into the bloodstream is common in patients subjected to dental procedures such as tooth extraction, endodontic treatment, and periodontal surgery, and during routine oral care. Streptococcus mutans, the primary etiological agent of dental caries, is frequently involved in coronary heart disease, such as infectious endocarditis. Recent studies identified S. mutans as the most prevalent bacterial species found in patients subjected to heart valve and atheromatous plaque surgery.

Objectives: Test the capacity of thirteen strains of S. mutans to invade primary human coronary artery endothelial cells (HCAEC).

Methods: Antibiotic protection assay (APA) and transmission electron microscopy (TEM) were used to access the invasive properties of the selected strains.

Results: Serotype e and f strains of S. mutans were capable of invading HCAEC as efficiently as Porphyromonas gingivalis. Among the tested strains, serotype f S. mutans OMZ175 displayed the most invasive behavior. Strains belonging to serotype c, the most prevalent S. mutans serotype in dental plaque, did not display an invasive behavior.

Conclusions: In this study, we demonstrated that by TEM and APA that S. mutans OMZ175 is capable of attaching to HCAEC and of gaining access to the cell cytoplasm. S. mutans can remain viable in the cytoplasm of HCAEC for prolonged periods (29 h). Our finding brings a new concept on the pathogenesis of S. mutans and its role in coronary heart disease.