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

Which dsdna is imprtant for dna purification, Which of the following proper...

Which of the following properties of dsDNA is imprtant for DNA purification? A. Hydrophilic B. Positively charged phosphate backbone C. Can only bind to divalent cations

Define the process of dough formation, Define the process of Dough Formatio...

Define the process of Dough Formation? You already know that gluten is the protein found in wheat. A unique property of gluten proteins of wheat grain endosperm (and to a lesse

Standard titration - estimation of vitamin c in lemon juice, Explain Standa...

Explain Standard titration - Estimation of Vitamin C in Lemon Juice? Pipette 5 ml of standard ascorbic acid solution into a 100 ml conical flask. Fill the burette with the dye s

Solar energy input, Solar Energy Input We know that the spectral distri...

Solar Energy Input We know that the spectral distribution and the intensity of solar radiation incident on the earth's surface are known. Of the enormous'amount of energy that

Functions of ecosystem, Ecosystems main functions are physical, chemical an...

Ecosystems main functions are physical, chemical and biological processes. Which is required for if maintenance of ecosystem. Some important function- 1.        Production of bi

What are the different organs of the respiratory system, The different orga...

The different organs of the respiratory system  Nostrils through which we inhale air in the nasal cavity  Pharynx  Larynx  Trachea (wind pipe)  Lungs - Bronchi,

Explain carbohydrates requirement during thyphoid, Explain carbohydrates re...

Explain carbohydrates requirement during thyphoid Carbohydrates: Carbohydrate intake should be liberal. This can be attributed  to: 1.  Repletion of glycogen stores. 2.

How are parasites classified, Concerning the number of hosts how are parasi...

Concerning the number of hosts how are parasites classified? Parasites that need only one host are known as monoxenous parasites. Parasites that need more than one host for th

Digestion of proteins, Digestion  of proteins Digestion  of proteins  ...

Digestion  of proteins Digestion  of proteins  is  initiated  in  the  stomach by pepsin.  Pepsin  acts upon food proteins  and  converts them  to proteoses  and  peptones whic

#biology tutor title.., When nd how i can srt my online work in this site q...

When nd how i can srt my online work in this site question #Minimum 100 words accepted#

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