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 enantiomers, Enantiomers: Select one: a. Have the same molec...

Enantiomers: Select one: a. Have the same molecular weight b. Have the same connectivity c. Are mirror images d. Are non-superimposable e. All of the above

What is probing depth, What is Probing depth Probing depths can be infl...

What is Probing depth Probing depths can be influenced by the tissue type- shallow depths are associated with a keratinized collar, whereas deeper depths are associated with mo

Explain the behaviour of pteridophytes, Q. Why are pteridophytes better ada...

Q. Why are pteridophytes better adapted to dry land than bryophytes? Were pteridophytes always less abundant than phanerogamic plants? Although pteridophytes and bryophyt

State the objectives of neuropsychological assessment, State the goals of N...

State the goals of Neuropsychological assessment Neuropsychological assessment therefore has twin goals. i) The first goal is to recognize the disrupted psychological compo

Define energy requirement for cancer patients, Define Energy Requirement fo...

Define Energy Requirement for Cancer Patients? It must be clear to you that cancer imposes increased energy demands because of the hyper-metabolic state of the disease process

Different types of stems, Different types of stems (a)  Monocots. Secur...

Different types of stems (a)  Monocots. Secure stems of various plants such as bamboo, sugar cane and corn. Cut every of the stems crosswise with a very sharp knife or razor bl

What are the pancreas, Pancreas Insulin (β cells) Promotes glucose en...

Pancreas Insulin (β cells) Promotes glucose entry in many cells, and in this way controls carbohydrate metabolism. Glucagon (α cells) Increases synthesis and release of

Explain hyperthermophilic organisms, Some hyperthermophilic organisms that ...

Some hyperthermophilic organisms that grow in highly acidic (pH2) habitats belong to the two groups: 1. Eubacteria and archaea 2. Cyanobacteria and diatoms 3. Protists and

Protist, Members of phylum animal like protist that are only free living

Members of phylum animal like protist that are only free living

What is osteoblast, What is osteoblast The osteoblast is the key for th...

What is osteoblast The osteoblast is the key for the development of new bone. It is essential that a large number of osteoblasts accumulate on the implant surface(contact osteo

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