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

How is the respiratory system in aquatic molluscs, How is the respiratory s...

How is the respiratory system in aquatic molluscs divided? What adaptive respiratory structure do terrestrial molluscs present? Aquatic molluscs oxygenate their blood through g

Define clostridium perfringens-associated gastroenteritis, Q. Define Clostr...

Q. Define Clostridium perfringens-associated gastroenteritis? Clostridium perfringens-associated gastroenteritis is a food borne disease which is frequently reported and is

Homopolysaccharides, HOMOPO L YSACCHARIDE S (= HOMOGLYCANS) These...

HOMOPO L YSACCHARIDE S (= HOMOGLYCANS) These are complex carbohydrats that are formed by repeated condensation or polymerisation of only one type of monosaccharide monome

Illustrate about whey protein, Illustrate about Whey protein Whey prote...

Illustrate about Whey protein Whey protein concentrate (WPC) is a highly nutritious ingredient manufactured from fresh dairy whey and it is spray dried to provide an excellent

What is bioremediation, Q. What is bioremediation? The Bioremediation i...

Q. What is bioremediation? The Bioremediation is the use of microorganisms, like protists, bacteria and fungi to degrade noxious substances turning them into non toxic or less

Why diabetics patient should have vegetables every day, Why Diabetics patie...

Why Diabetics patient should have Vegetables every day Diabetics should have vegetables every day. Fresh vegetables are to be preferred because they have less fats and salt. Da

What is sanning membrane proteins, Which of the following is true for the f...

Which of the following is true for the following spanning membrane proteins? A. The mAChR (muscarinic Acetylcholine Receptor) is a spanning membrane protein located in the memb

Microorganisms acquired during transport of raw food, Microorganisms Acquir...

Microorganisms Acquired During Transport, Handling and Processing of Raw Foods Microorganisms can come from truck, tanker, food handlers and equipment and utensils used in the

Explain in brief about leukotrienes and prostaglandins, Leukotrienes and pr...

Leukotrienes and prostaglandins are produced only when the mast cell undergo degranulation and enzymatic break down of phospholipids in the plasma membrane. The effects formed b

Describe chemical changes in fruits and vegetables, Describe Chemical chang...

Describe Chemical changes in fruits and vegetables The detailed chemical changes that occur when fruits and vegetables are boiled in water or steamed, canned, dried or frozen,

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