Related Experiment Videos
Procoagulant activity of endocardial vegetations and blood monocytes in rabbits with Streptococcus sanguis
A G Buiting1, J Thompson, D van der Keur
1Department of Infectious Diseases, University Hospital, Leiden, The Netherlands.
Abstract:
To investigate activation of the coagulation system in bacterial endocarditis, we determined the procoagulant activity of blood monocytes isolated from rabbits with Streptococcus sanguis-infected or sterile catheter-induced endocardial vegetations. This activity was determined directly after isolation from the peripheral blood and after stimulation in vitro by either endotoxin or by phagocytosis of S. sanguis. The procoagulant activity of the vegetations of these rabbits was also determined. The procoagulant activity of blood monocytes of rabbits with S. sanguis endocarditis was found to be similar to the activity of monocytes of rabbits with sterile vegetations, both at the time of isolation and after stimulation in vitro by exposure to endotoxin or phagocytosis of bacteria. The procoagulant activity of infected vegetations was significantly higher than that of sterile vegetations. We conclude that in bacterial endocarditis the coagulation system is activated locally at the site of the vegetation. Triggering probably occurs by thromboplastin generated by monocytes activated by phagocytosis of bacteria on the vegetational surface.
Insights
Bacterial endocarditis activates the coagulation system locally within vegetations. Monocytes play a key role in triggering this response through bacterial phagocytosis on the vegetation surface.
Area of Science:
- Microbiology
- Hematology
- Pathology
Background:
- Bacterial endocarditis involves infection of heart valves.
- Activation of the coagulation system is implicated in this condition.
Purpose of the Study:
- To investigate the role of monocytes and vegetations in coagulation activation during bacterial endocarditis.
- To determine if coagulation activation occurs systemically or locally.
Main Methods:
- Isolated blood monocytes from rabbits with Streptococcus sanguis-induced or sterile endocardial vegetations.
- Assessed monocyte procoagulant activity ex vivo after stimulation with endotoxin or bacterial phagocytosis.
- Measured procoagulant activity of infected and sterile vegetations.
Main Results:
- Monocyte procoagulant activity was similar in both infected and sterile endocarditis models, both before and after in vitro stimulation.
- Procoagulant activity of infected vegetations was significantly higher than that of sterile vegetations.
Conclusions:
- Coagulation system activation in bacterial endocarditis is primarily a local event at the vegetation site.
- Monocyte-derived thromboplastin, generated by phagocytosis of bacteria on the vegetation, likely triggers local coagulation activation.