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

Amnion adaptation to terrestrial life, Q. Why can the amnion also be consid...

Q. Why can the amnion also be considered an adaptation to terrestrial life? The amnion is as well an adaptation to dry land since one of its functions is to prevent desiccation

How to placing the implants in immature grafted, Placing the Implants in Im...

Placing the Implants in Immature Grafted Sites One of the most common causes of prosthetically related implant failure is believed to be the too rapid loading of the implant su

Deficiency diseases-copper deficiency, Deficiency of vitamin -A (hypovitami...

Deficiency of vitamin -A (hypovitaminosis-A) Vitamin A deficiency develops due to insufficient supply of the vitamin or its defective absorption from alimentary tract. The defi

Bio-informational homework, Determine sequence weights for the sequences AC...

Determine sequence weights for the sequences ACTA, ACTT, CGTT, and AGAT in problem 1 by using Thompson, Higgins, and Gibson method

Define the soybean protein isolates, Define the Soybean Protein Isolates? ...

Define the Soybean Protein Isolates? Soy protein isolates are the most pure and refined soy protein available. Isolated soybean proteins (ISP), or soybean protein isolates, are

What is reduction, What is reduction? The most commonly understood defi...

What is reduction? The most commonly understood definition of reduction is the removal of oxygen or addition of hydrogen ions. However, chemically, reduction can be defined as

Drawbacks of lamellar model, Drawbacks of Lamellar model This model ...

Drawbacks of Lamellar model This model does not explain the elasticity of PM. Although this model says that PM is elastic but it also states that head of lipid molecules is

Why ammoniotelic excretion occur, Why after the passage of animals from the...

Why after the passage of animals from the aquatic to the terrestrial habitat does the abandonment of the ammoniotelic excretion occur? Ammonia is a highly toxic molecule if not

Accidents resulting in death, Accidents Resulting in Death Accidents t...

Accidents Resulting in Death Accidents that cause death are dealt with in a different way. The law requires full compensation to the widow for complete life or until remarriag

Determine lamellar compaction and remodeling, Lamellar compaction and remod...

Lamellar compaction and remodeling (6 to 18 weeks) A remodeling phase is initiated in which hematopoietic-derived osteoclastic cells form cutting cones will remove the establis

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