The Killer of 1.8 Billion People a Year: M. tuberculosisGurpreet PandherMMI 113Dr. Judith GnarpeThroughout our lives many of us have had medical exams where we have come across a tuberculosis skin test to test us for tuberculosis. Although we may have gained some knowledge of the disease tuberculosis, as students of medical microbiology it is important to understand the causative mycobacterium behind it, as well as the disease and the treatment for the disease. Many non-pathogenic mycobacteria are part of the normal flora of the fatty or dry parts of our body, however Mycobacterium Tuberculosis is not one of them. The causative agent of tuberculosis disease (TB) is in fact Mycobacterium Tuberculosis (discovered by Robert Koch). 4 This deadly disease is the leading cause of death from bacterial infection, affecting 1.8 billion people per year. In the United States, an overall decline in the rate of tuberculosis has been reported (the lowest recorded figure is 4.4 cases/100,000 people) and there is also a decrease in drug-resistant multiple tuberculosis.2 However, tuberculosis is on the rise in foreign-born individuals (Compared to the United States) with a 9.7-fold higher tuberculosis rate difference for foreign-born individuals.2 Mycobacterium Tuberculosis (M. tuberculosis) comes from the Mycobacteriaceae family and is a bacterium bacillus (rod-shaped); each rod is 0.2-0.5 um wide and 2-4 micrometers long.1 M. tuberculosis is non-motile and is an obligate aerobe, which is justified by the fact that the MTB complexes are located in the upper lobes of the lungs which they are highly ventilated. The bacterium also does not form spores and is not encapsulated. M. tuberculosis does not retain stains thanks to the high quantity of lipids present in the wall, creating a "waxy... papery centre..." resistant not only to first-line drugs but also to second-line injectable drugs. Patients with XDR tuberculosis have less effective treatment options and outcomes.2 A vaccine called BCG (bacillus Calmette and Guerin) is available against MTB. BCG is a live strain of Mycobacterium Bovis and has remained avirulent for approximately 60 years.2 The vaccine is 60-80% effective and is not administered in the United States for several reasons. First of all, BCG only prevents complications of the disease such as meningitis, but does nothing against the prevention of infection by the bacterium. It is useful for countries where tuberculosis rates are high and the vaccine is administered to those who are at high risk of contracting the infection (family of tuberculosis patients).3 Furthermore, the vaccine cannot stop the reactivation of the disease in subjects who have faced the disease. previous infection/disease in their life.2Reference