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

Human respiratory system - thoracic cavity, THORACI C CAVITY - Thor...

THORACI C CAVITY - Thoracic cavity is air tight. On dorsal side vertebral column present. On ventral side sternum present. On lateral side 12 pairs ribs present. On p

Define needs of fluid in postoperative nutritional care, Define Requirement...

Define Requirements of Fluid in Postoperative Nutritional Care Extensive fluid losses may occur through vomiting, haemorrhage, diesis, excudate, fever and sweating after a surg

What do you mean by trachea, Q. Why doesn't the food enter the trachea inst...

Q. Why doesn't the food enter the trachea instead of going to the esophagus? When food is swallowed the swallow reflex is activated and the larynx closes and elevates to avoid

Determine energy requirements for athletes, Determine Energy Requirements f...

Determine Energy Requirements for Athletes? You are familiar with the fact that body needs' energy to maintain body temperature, to meet metabolic demands, maintain electrolyte

How bone density affect osseointegration, How Bone density affect Osseointe...

How Bone density affect Osseointegration The most important bone property is density which is influenced by factors such as patient age and genetics. Higher density bones have

Main effects of chronic lead, Q. Main effects of chronic lead? Lead, e...

Q. Main effects of chronic lead? Lead, even at relatively low levels of exposure can cause severe health effects. Exhaust from vehicles using unleaded petrol serves as

Explain prevalence in coronaw artery disease, Explain Prevalence in coronaw...

Explain Prevalence in coronaw artery disease ? The first report to highlight the high prevalence of CAD among Indian expatriates came from an autopsy study done in Singapore. C

Electron transport chain, ELECTRON TRANSPORT CHAIN All processes requir...

ELECTRON TRANSPORT CHAIN All processes require energy. In living cells, we constantly use energy for a number of biochemical reactions e.g. muscular movements, synthesis  of ne

Cells, List structures found in unicellular organisms that are an adaptatio...

List structures found in unicellular organisms that are an adaptation to their free-living life and are not usually found in the cells of multicellular organisms.

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