Pathogenesis, Biology

Assignment Help:

The interactions between the human host and selected microorganisms that culminate in IE involve the vascular endothelium, hemostatic mechanisms, the host immune system, gross anatomic abnormalities in the heart, surface properties of microorganisms, and peripheral events that initiate bacteremia. Endothelial damage results in platelet-fibrin deposition, which in turn is more receptive to colonization by bacteria than is the intact endothelium. It is hypothesized that platelet-fibrin deposition occurs spontaneously in persons vulnerable to endocarditis and that these deposits, called nonbacterial thrombotic endocarditis (NBTE) are the sites at which micro organisms adhere during bacteremia to initiate IE. Bacteremia is the initiating event that ultimately converts NBTE to IE.  Bacteremia rates are highest for events that traumatize the oral mucosa, particularly the gingiva, and progressively decrease with procedures involving the genitourinary tract and the gastrointestinal tract.

The platelet-thrombin deposits are found at the valve closure-contact line on the atrial surfaces of the mitral and tricuspid valves and on the ventricular surfaces of the aortic and pulmonic valves, the sites of infected vegetations in patients with IE. Three hemodynamic circumstances may injure the endothelium, initiating NBTE: (1) a high velocity jet impacting endothelium (2) flow from a high to a low pressure chamber and (3) flow across a narrow orifice at high velocity.  Flow through a narrowed orifice, as a consequence of venturi's effect, deposits bacteria maximally at the low-pressure sink immediately beyond an orifice or at the site where a jet stream impacts a surface.

To cause IE, the organism must be able to persist and propagate on the endothelium. This requires resistance to host defenses. The complement-mediated bactericidal activity of serum limits the ability of susceptible aerobic gram-negative bacilli to cause IE. Those organisms that most frequently cause endocarditis adhere more vigorously in vitro to cardiac valves than do organisms that rarely cause IE.


Related Discussions:- Pathogenesis

Explain acyclovir, Explain Acyclovir Available in topical, oral, and in...

Explain Acyclovir Available in topical, oral, and intravenous (IV) formulations, acyclovir is used to treat herpes simplex virus (HSV) and varicella-zoster virus (VZV) infectio

Name the important inorganic molecular for living being, What are the most ...

What are the most significant inorganic molecular substances for living beings? The most significant inorganic substances for living beings are mineral salts, water, carbon dio

Explain adverse effects of enfuvirtide, Adverse effects of Enfuvirtide ...

Adverse effects of Enfuvirtide Almost all patients make local injection site reactions to enfuvirtide, usually having of mild or moderate pain, erythema, induration, nodules an

Endocytosis and exocytosis, Endocytosis and Exocytosis Endocytosis is the...

Endocytosis and Exocytosis Endocytosis is the process by which substances are brought into the cell from outside by formation of membrane bound vesicles. These extra cellular sub

Cell cycle, Provide a link to the graph, describe the variables, and interp...

Provide a link to the graph, describe the variables, and interpret the meaning of the graph

Infectious canine hepatitis, Infectious canine hepatitis The disease i...

Infectious canine hepatitis The disease is caused by type-1 canine Adenovirus in the family Adenoviridae. The disease appears in pups as peracute, acute, and mild. The clinica

Hemoconcentration, Hemoconcentration Before, during and after CPB, hem...

Hemoconcentration Before, during and after CPB, hemoconcentration allows the patient's blood to be salvaged during surgery to help reduce the need for donor blood. Ultra

Noise pollution - environmental pollution, Noise Pollution - Environmental ...

Noise Pollution - Environmental Pollution Noise is unwanted sound or excessively high levels of sound. Noise pollution is not only an annoyance, but at sufficiently high level

Illustrate about the neuropsychological assessment, Illustrate about the ne...

Illustrate about the neuropsychological assessment A neuropsychological assessment is a clinical examination of both the working brain and dysfunctional brain. Neuropsychologic

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd