Streptococcus mutans in atherosclerotic plaque: Molecular and immunohistochemical evaluations

Objectives: To verify the presence of Streptococcus mutans (S. mutans) in atherosclerotic plaque (AP) using techniques with different sensitivities, correlating with histological changes in plaque and immunoexpression of inflammatory markers. Materials and Methods: Thirteen AP samples were subjected to real-time polymerase chain reaction (qRT-PCR), histopathological analyses, histochemical analysis by Giemsa staining (GS), and immunohistochemical analysis for S. mutans, IL-1 beta, and TNF-alpha (streptavidin-biotin-peroxidase method). Ten necropsy samples of healthy vessels were used as controls. Results: All AP samples showed histopathological characteristics of severe atherosclerosis and were positive for S. mutans (100.0%) in qRT-PCR and immunohistochemical analyses. GS showed that Streptococcus sp. colonized the lipid-rich core regions and fibrous tissue, while the control group was negative for Streptococcus sp. IL-1 beta and TNF-alpha were expressed in 100% and 92.3% of the AP tested, respectively. The control samples were positive for S. mutans in qRT-PCR analysis, but negative for S. mutans, IL-1 beta, and TNF-alpha in immunohistochemical analyses. Conclusion: The detection of S. mutans in AP and the visualization of Streptococcus sp. suggested a possible association between S. mutans and atherosclerosis. The results obtained from the control samples suggested the presence of DNA fragments or innocuous bacteria that were not associated with tissue alteration. However, future studies are necessary to provide more information.

Automated summary

The study found the presence of Streptococcus mutans in atherosclerotic plaque, suggesting a possible association between the bacteria and atherosclerosis. Control samples showed the presence of harmless bacteria not associated with tissue alteration. Further studies are needed for more information.