Pathogenesis of infective endocarditis
المؤلف:
APURBA S. SASTRY , SANDHYA BHAT
المصدر:
Essentials Of Medical Microbiology 2021
الجزء والصفحة:
3rd edition , p287-288
2025-10-20
66
The pathogenesis of infective endocarditis involves the following sequential steps.
- Underlying risk factors: IE is usually predisposed by various risk factors
* Underlying cardiac defect: The cardiac conditions most commonly associated with infective endocarditis are congenital valvular diseases such as mitral regurgitation, aortic stenosis, aortic regurgitation, ventricular septal defects
* Use of intravenous catheter
* Prosthetic valve replacement surgery.
- Endothelial injury: The endothelium, unless damaged, is resistant to infection by most bacteria and to thrombus formation
* Therefore, though IE can develop on previously normal valves, but it is more common to develop on a defective valve
* This is because predisposing cardiac abnormalities produces turbulence in blood flow to the heart which can damage cardiac endothelium. Use of IV catheter induces direct trauma that can damage cardiac endothelium
* This damage to the endothelial surface results in the deposition of platelets and fibrin—a condition called nonbacterial thrombotic endocarditis (NBTE).
- Colonization: The thrombus subsequently serves as a site of bacterial attachment during transient bacteremia. When bacteria transiently gain access to the bloodstream (e.g. after brushing the teeth), the organisms may stick to and then colonize the damaged cardiac endothelial surface
- Formation of vegetations: After colonization, the endothelial surface gets rapidly covered with a protective layer of fibrin and platelets. This protective environment is favorable to further bacterial multi plication. This web of platelets, fibrin, inflammatory cells, and entrapped organisms is called as vegetation (Fig. 1)
- Metastasis: The resulting vegetations ultimately seed bacteria into the blood at a slow but constant rate, which can metastasize to distant sites.
Fig1. Subacute bacterial endocarditis involving mitral valve showing large vegetations on valve leaflets. Source: Public Health Image Library, ID # 851 (Dr Edwin)/ Centers for Disease Control and Prevention (CDC), Atlanta (with permission).
الاكثر قراءة في مواضيع عامة في علم الامراض
اخر الاخبار
اخبار العتبة العباسية المقدسة
