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

What are cilia and flagella, Cilia and flagella are structures found in var...

Cilia and flagella are structures found in various prokaryotes as well in some eukaryotic cells. They play defense, nutrition and movement roles for the cell. In eukaryotic cells o

Explain the stages of alzheimer''s disease, Explain the Stages of alzheimer...

Explain the Stages of alzheimer's disease? Stage I - There is an increased forgetfulness, anxiety and depression. Associated nutrition related changes include difficulty in

Explain stage of total biological inactivity, Is the stage when an insect l...

Is the stage when an insect larva is within a cocoon a stage of total biological inactivity? The period when the larva is inside its cocoon is a time of intense biological acti

Floral induction, Floral Induction The transformation of vegetative ap...

Floral Induction The transformation of vegetative apex into a floral apex is a multifactor and multistep phenomenon. Despite researches on flowering carried out during the las

Determine the genotypes of parents, In humans, the recessive allele that ca...

In humans, the recessive allele that causes a form of red-green colour blindness (c) is found on the X chromosome. a) Determine the genotypes and phenotypes of the F1 generation fr

Feeding habit, what is the mode nutrition exibited by tape worm?

what is the mode nutrition exibited by tape worm?

Difference between the exocrine and endocrine gland, Q. What is the differe...

Q. What is the difference between the exocrine gland and the endocrine gland? Endocrine gland is a gland whose secretions are called as hormones that are collected by the blood

How to measure post repair prv/iv pressure, How to measure Post Repair Prv/...

How to measure Post Repair Prv/iv Pressure ? In the operating room, after coining of1 bypass and before removing cannulae the RV and LV pressures are measured. The pressures ar

Define different uses of additives in food, Normal 0 false fa...

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

Define counter stain - staining technique, Define Counter Stain - Staining ...

Define Counter Stain - Staining Technique? Finally, the smear is counter stained with a simple basic dye different in colour from crystal violet. Safranin is the most commonly

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