Saturday, January 24, 2015

Week 3: Etiology and Pathophysiology

Today we have to take a look back to our discussion in week one.  But now I am going to help you understand what causes meningococcal meningitis, and how the meningitis comes to be.  Three conditions need to be present in order for the disease to occur. 1) You must be exposed to the pathogen.  2) You must acquire a strain that can cause disease.  3)  The bacteria must be able to invade (Manchanda, Gupta, Bhalla, 2006). 

The most prominent offender in this case is the bacterium Nisseria meningitides (Hoffman, Weber, 2009).  This bacterium can sit inside of a human who does not even realize it.  The most common place for the bacteria to sit is in the nasal cavity.  As we also discussed before, this bacteria can travel from person to person by sneezing, kissing, sharing drinks, and other ways that swap saliva.  Then sometimes, that bacteria finds the perfect host, such as one with damaged lining of the respiratory tract.  Just like cars, there are multiple models of the bacteria.   Serogroups A, B, and C contain capsules around itself and are the most likely to cause damage (Manchanda, Gupta, Bhalla, 2006).  If the bacteria has the ability to work its way into the blood stream, it can multiply to increasingly high numbers.  By way of the blood, the bacteria can travel to the brain and leak out, reaching the layers of the meninges surrounding the brain as well as spinal cord (Pathan, Faust, Levin, 2003).

As soon as the bacteria enter the blood, the body realizes that something is not right.  The body is able to detect the bacterium’s endotoxin.  The body’s inherent response is to attack these foreign invaders (Pathan, Faust, Levin, 2003).  Our natural defenders, the immune system, try’s to swoop in and get rid of the offender.  Our body’s best way to destroy these unwanted bacteria is through regulated processes of inflammation.  The endotoxin continues to send red flags to the immune system, which allows inflammation of the meninges to continue (Hoffman, Weber, 2009).  The bacteria also cause microvascular damage due to its presence in the bloodstream that the immune response that occurs.  This damage includes increased ability for blood to exit the vascular system, improper constriction and dilation of arteries, the loss of the ability for blood to clot, and decreased heart function (Pathan, Faust, Levin, 2003).

The impaired central nervous system (brain and spinal cord) can be seen as a result of both direct invasion of the meninges, and a location receiving the septic blood by the vascular permeability (Pathan, Faust, Levin, 2003).  Many individuals develop a raised pressure inside of the brain due to the inflammatory process and edema that is occurring.  Since the skull is a hard container, and the brain is squishy, the brain shifts in order to make room for this new pressure.  Many of these patients are at risk for loss of consciousness and decreased blood volume being able to reach the brain, which contains the oxygen that we need for the brain to survive (Pathan, Faust, Levin, 2003). 

Here is a link to a video animation of the process! Below are also scholar articles that are more in depth to the Pathophysiology of the disease! https://www.youtube.com/watch?v=j3SdmgYBs4E



BIBLIOGRAPHY:

Hoffman, O., Weber, R. (November, 2009). Pathophysiology and Treatment of Bacterial Meningitis. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002609/

Manchanda, V., Gupta, S., Bahalla, P., (2006) Meningococcal Disease: History, epidemiology, pathogenesis, clinical manifestations, diagnosis, antimicrobial susceptibility, and prevention. Retrieved from http://www.ijmm.org/article.asp?issn=0255- 0857;year=2006;volume=24;issue=1;spage=7;epage=19;aulast=Manchanda

Pathan, N., Faust, S., Levin, M. (2003). Pathophysiology of Meningococcal Meningitis and Septicemia. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1763171/pdf/v088p00601.pdf
                                                                                              
Shipley, C. (October, 2012) Bacterial Meningitis Video. Retrieved from https://www.youtube.com/watch?v=j3SdmgYBs4E



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