A Research Essay On Tuberculosis

The Killer of 1.8 billion/year: M. tuberculosis

Gurpreet Pandher

MMI 113

Dr. Judith Gnarpe

Throughout our lives many of us have gotten medical examinations in which we come across a TB skin test to test us for Tuberculosis. Although we may have gained some knowledge of the disease Tuberculosis, as Medical Microbiology students it is important to understand the causative mycobacterium behind it, as well as the disease and treatment for the disease. Many non-pathogenic mycobacterium are apart of the normal flora of the oily or dry parts of our body, however Mycobacterium Tuberculosis is not one of them. The etiological agent of the disease tuberculosis (TB) is in fact Mycobacterium Tuberculosis (Discovered by Robert Koch). 4 This deadly disease is the leading cause of death from a bacterial infection and it has affected 1.8 billion people/year. In the United States the TB rate has been reported to decrease overall (At the lowest recorded data being 4.4 cases/ 100,000 people) and also there is also a decrease in multiple drug resistant TB.2 However, TB is increasing in foreign-born persons (In respect to the United States) with the difference of TB rate being 9.7 times higher for foreign-born individuals.2

Mycobacterium Tuberculosis (M. tuberculosis) comes from the family Mycobacteriaceae and is a bacillus (rod shaped) bacterium; each rod being 0.2-0.5 um wide and 2-4 micrometers in length.1 M. tuberculosis is non motile and is obligate aerobe which is justified by the fact that MTB complexes are located at the upper lobes of the lungs which are highly aerated. The Bacterium is also non-spore forming and non-encapsulated. M. tuberculosis doesn’t retain any stains due to the high amounts of lipid in the wall creating a “waxy c...

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...esistant to not only the first-line drugs but also to the second line injectable drugs. XDR TB patients have less effective treatment options and outcomes.2

A vaccine called BCG (Bacillus of Calmette and Guerin) is available against MTB. BCG is a live strain of Mycobacterium Bovis and it has remained avirulent for about 60 years.2 The vaccine is 60-80% effective and is not administered in the United States because of several reasons. Firstly, BCG only prevents disease complications such as meningitis, but does nothing against preventing infection by the bacterium. It is useful for countries were Tuberculosis rates are high and the vaccine is given to those who are at high risk of becoming infected (family of TB patient).3 Also, the vaccine can’t stop disease reactivation in individual who have dealt with the infection/disease previously in their life.2

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