Federal Bacterium Investigators

Staphylococcus aureus

Mycobacterium tuberculosis

Trypanosoma brucei

Yersinia pestis

Lethal Fugitive: Mycobacterium tuberculosis

Charged with: Centuries of Mass Murder

 

Mycobacterium tuberculosis

The murderous character of Mycobacterium tuberculosis has general characteristics of rod-shaped structure, an obligate aerobe and a facultative intracellular parasite.

Discovered in 1882 by the Prussian physician Robert Koch, M. tuberculosis has been known over the years by many names, including Koch's bacillus.

M. tuberculosis has a remarkably slow generation time (15-20 hours) and are grown in small, buff colored colonies on two media - Middlebrook's medium (agar based) and Lowenstein-Jensen medium (egg based) (Source 1).

Mycobacterium tuberculosis, the murderer, does not subscribe to either Gram-positive nor Gram-negative classification, as it lacks chemical characteristics of both. M. tuberculosis' cell wall structure is unique, containing peptidoglycan -producing a very weak Gram-positive stain - but otherwise it is composed of complex lipids. The lipid of M. tuberculosis' cell wall consists of mycolic acids, cord factors and wax-D.

Mycolic factors form a lipid shell around M. tuberculosis as  hydrophobic molecules, affecting the permeability and determining the virulence of this killer. The cord facter is toxic to mammalian cells, and wax-D is the major component of Freund's complete adjuvant (Source 1)

Known as an acid-fast bacteria, this criminal is impermeable by certain dyes. However, once dyed, for example with a Ziehl-Neelsen acid-fast staining procedure, M. tuberculosis will retain dyes and stains despite many rigorous treatments. During Ziehl-Neelsen staining, the sample of M. tuberculosis is heat fixed on the slide, flooded with carbol fuschin stain, heated until steaming, poured off, washed with water, decolorized with acid-alcohol, washed again, then flooded with methylene blue counterstain and finally, washed with water. (Source 2)

Two M. tuberculosis colonies on Lowenstein-Jensen medium (egg based).

 

 

Pathophysiology of Mycobacterium tuberculosis

Mycobacterium tuberculosis in a scanning electron micrograph, magnification: 15549 times

Acid-fast stain of M. tuberculosis

M. tuberculosis, an ancient killer of mammals for thousands of years, can be kept under control by the immune system by its production of macrophages to surround the bacteria, forming a hard shell to contain the monster. This is only found when one has a tuberculosis infection, not the disease.

When the disease is found in the lungs, a chest x-ray will reveal lesion, sputum smears and cultures will be positive, as will the tuberculin skin test; cough, fever and weight loss will occur, and the victim will be infectious.

At first the infective "droplet nuclei" are inhaled and reach the alveoli of the lungs, and multiplies practically unrestricted, within inactivated "macrophages until the macrophages burst." (Source 1) Lymphocytes (T-cells) will attempt to fight M. tuberculosis will activate the ineffective macrophages as they liberate cytokines such as gamma interferon (IFN). The macrophages can now fight M. tuberculosis - which is now forming tubercles. Still inactivated macrophages are used by tuberculosis to replicate and grow the tubercle.  Spreading to other parts of the lung is common at this point, as well as the invasion of an artery (Source 1). This is known as milliary tuberculosis, which causes secondary lesions (exudative and granulomatous lesions). the tubercles continue to grow and rapidly multiplies, causes cavities to form and allows M. tuberculosis to spill into airways and take over the lung.

If you or a loved one presents with the following symptoms, Mycobacterium tuberculosis may be involved, and you should seek immediate medical attention:
  • Fever, night sweats
  • Weight loss, loss of appetite
  • Cough
  • Ceaseless fatigue

Unfortunately, M. tuberculosis is very difficult to cure due to the reaction the body takes to fight it. The human immune response produces granulomas, or waxy coatings over the bacteria that quarantine but do not kill, allowing M. tuberculosis to remain dormant. Further, researchers led by Godbardhan Das in New Delhi found that "T.B." protected itself by effectively hiding within the stem cells of the body, as these formed a protective coating around the granulomas and kept the bacteria safe from T-lymphocyte cell attack. (Source 4)

 

 

Threat Level:

Tuberculosis is known to have resistance to antibiotics, to death by acidic or alkaline compounds, "to osmotic lysis via complement deposition, to lethal oxidations and survival inside of microvages", and an impermeability to stains and dyes. (Source 1) M. tuberculosis is undoubtedly a "superbug," and most watched for by the FBI. It is lethal in that it is an airborne disease, making it harder to treat than other bacteria.

Though there are many numbers implicating the number of murders committed by "TB," the number settles around 2 to 3 million in deaths, and about a third of the world population is infected (latently or actively) by Mycobacterium tuberculosis. It is the leading killer of those infected with HIV, as it often finds the lack of T-cells in the HIV infected body a more easy take-over.

The disease is unfortunately found in greater numbers in specific populations, such as international travelers, correctional facility staff and inmates, the African-American community, disaster responders and those in less developed nations with lesser access to preventative health-care.

Ongoing studies regarding cures continue, however at the present time the cure for the usual "TB" infection take approximately 6 months, according to the European Respiratory Journal article, "Tuberculosis therapy: past, present and future." (Source 5). This is an especially significant and uninspiring time in regard to those infected around the globe with little access to proper treatment and care, as the time frame for being cured dramatically increases the lesser quality of resources and care granted. In the future, this amount of time to be considered cured of this dreadful disease is hopefully to be lengthened, as studies continue to seek this goal. 

A lung infected with fatal Mycobacterium tuberculosis

 

 

Protect Yourself and Your Loved Ones

Mycobacterium tuberculosis digital image at 10 times magnification

Mycobacterium tuberculosis stained red against tissue (dyed blue) in a Ziehl-Neelsen stain

The following misconceptions do not spread the disease:
  • Sharing food or drink
  • Kissing
  • Shaking someone's hand
  • Sharing toothbrushes
  • Touching toilet seats or bed linens

Those at risk for progressing the "latent TB infection" to active TB disease  are:

  • Immune compromised, like those infected with HIV
  • Those infected with TB in the past 2 years or were not treated correctly in the past
  • Babies, young children and the elderly
  • Those who inject illegal drugs

(Source 3)

Prevention is best met with prompt detection, airborne precautions, and immediate treatment.  If you believe you have been exposed to a victim of this murderous "superbug", contact your doctor immediately for the TB skin test. (Source 3) Also, prevent exposure when traveling abroad, especially those working in health-care settings.

Further, there exists the bacille Calmette-Guerin vaccine, which is often granted to high-risk infants (in areas where Mycobacterium tuberculosis is prevalent and less controlled).

Click here for more information from other great organizations regarding Mycobacterium tuberculosis

 

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