Bacterial adherence to human endothelial cells in vitro.

Area of Science:

• Microbiology
• Pathogenesis
• Infectious Diseases

Background:

• Bacterial adherence to host tissues is crucial for pathogen colonization and infection.
• Acute bacterial endocarditis involves infection of heart valves, often by specific bacterial species.
• Understanding bacterial-endothelial cell interactions is vital for explaining pathogen tropism and virulence.

Purpose of the Study:

• To investigate the in vitro adherence of various bacterial species to human endothelial cells.
• To determine if bacterial adherence correlates with pathogenicity in acute endocarditis.
• To elucidate the mechanism of bacterial interaction with endothelial cells.

Main Methods:

• Developed an in vitro adherence assay using confluent human endothelial cell monolayers.
• Tested adherence of 32 Gram-positive and Gram-negative blood culture isolates.
• Utilized transmission electron microscopy to visualize bacterial-endothelial cell interactions.

Main Results:

• Staphylococcus aureus strains exhibited high adherence to endothelial cells.
• Serratia marcescens showed significant adherence, while most other isolates, including viridans streptococci, were nonadherent.
• Transmission electron microscopy revealed Staphylococcus aureus attachment, invagination, and intracellular engulfment by endothelial cells.

Conclusions:

• Bacterial adherence to endothelial cells is a critical factor in acute endocarditis pathogenesis.
• Staphylococcus aureus's preferential adherence and uptake by endothelial cells contribute to its virulence and ability to cause metastatic infections.
• Adherence assays provide a valuable model for studying bacterial pathogenicity in endovascular infections.