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
Reference
A low-grade fever, weight loss, lethargy, night sweats, respiratory congestion, cough, and hemoptysis, are symptoms indicative of Tuberculosis. A positive skin test, abnormal chest x-ray and a positive sputum culture are indicators of Tuberculosis. Tuberculosis is transmitted by inhalation of respiratory droplets containing bacteria. This excerpt depicts tuberculosis and its history and prevalence.
Tuberculosis or TB, referred to by some as the White death due to the epidemic that arose in Europe that lasted two hundred years, is usually caused by in humans by a microorganism by substrains of Mycobacterium tuberculosis. It’s hard to determine the exact years in which TB first infected humans, but since the disease leaves traces on the bone in can be found in archeological record and it is believed to go all the way back to the B.C. era. Although it is hard to tell if the bone damage was truly from TB, there is research that shows that it has been around since the 17th and 18th centuries with a high number of incidences of TB, and in 1882 Dr. Robert Koch announced that his discovery of the causing factor of TB, which is Mycobacterium tuberculosis. A tuberculosis bacterium is spread through the air by an infected person speaking, coughing, or sneezing. Due to the fact the bacteria is protected by a waxy cell all, the body’s defense takes weeks to develop any kind of immunity and it allows the bacteria to exponentially multiply freely within the body. If TB it’s left untreated it will eat rapidly through many tissues, usually beginning with the lungs, lymph nodes, and kidneys. As the infection spreads to the lungs, it causes a cough and fluid between the chest wall and lungs, which leads to chest pains, severe shortness of breath, and potential heart failure. TB also infects bones and joints that can produce arthritis like pain and characteristic bone damage. Another possibility is that it may affect the fluid around the brain, causing meningitis, which can lead to fever, drowsiness, and eventually coma and death (Wingerson, 2009).
Tuberculosis is an air-borne disease, hence, it can be passed from an infected person to a healthy individual through coughing, sneezing and other salivary secretions. Tuberculosis is caused by the transfer of Mycobacteriun Tuberculosis (M. Tuberculosis) also known as Tubercle Bacillus, a small particle of 1-5 microns in diameter, due to the small size, when an infected person sneezes or coughs, about 3,000 particles are expelled. M. Tuberculosis responsible for tuberculosis is able to stay in the air for a long period of time (about 6hoursAnother way of acquiring Tuberculosis is by drinking unpasteurized milk, milk straight from cow, although this is not a common mode of transmission, it can be found in rural areas. Ingestion of contaminated cow milk transmits Mycobacterium Bovis, the animal form which is still potent enough to cause tuberculosis in humans. ). Tuberculosis transmission is affected by exposure, socioeconomic status of person, proximity, immune status of uninfected individual (%&&%&? CDC).
Education can be a powerful weapon in fighting tuberculosis in the United States also around the world. Today, it is encouraging how so many people know how TB contracts human and what cause drug resistant effects among those who are under TB treatment.
Although some infections are unique enough to be identified clinically, usually microbiologic laboratory methods are needed to identify the etiologic agent and diagnose microbial infection (Washington, J.A., 1996). Although we have made significant progress in our ability to diagnose and treat infectious diseases, they still remain a strong challenge to human survival, for example the disease Tuberculosis caused by a microbial infection with Mycobacterium tuberculosis accounted for one third of the worlds bacterial infections in 2010 infecting a total of 8.8 million people worldwide (Dheda et al., 2010).
In the modern day, Tuberculosis is almost exclusively a threat to third-world and developing nations. It is hard, as members of a modern, industrialized nation, to understand TB's force and its worldwide ramifications without having done research of some sort on the disease. As Americans, the people of this country are almost absolved from feeling any affects of the disease whatsoever. It was not always this way.
Mycobacterium tuberculosis (MTB) is the main causative organism which attacks the lungs but can also infect other organs of the body. M.tuberculosis is an intracellular pathogen that is highly adapted to human.7The bacterium spread primarily through aerosolized infectious particles generated from coughing and sneezing by individuals with pulmonary tuberculosis and less commonly via skin wounds 8. The most important factors influencing the current TB epidemic in resource poor setting are closely related to malnutrition, overcrowded living conditions and lack of access to free or affordable health care services.9
Tuberculosis or TB is an airborn infection caused by inhaled droplets that contain mycobacterium tuberculosis. When infected, the body will initiate a cell-mediated hypersensitivity response which leads to formation of lesion or cavity and positive reaction to tuberculin skin test (Kaufman, 2011). People who have been infected with mycobacteria will have a positive skin test, but only ones who have active TB will show signs and symtoms. Basic signs and symptoms include low grade fever, cough with hemoptysis, and tachypnea. They may also show pleuristic chest pain, dyspnea, progressive weight loss, fatigue and malaise (Porth, 2011).
"Chapter 6 Treatment of Tuberculosis Disease." . Centers for Disease Control and Prevention, n.d. Web. 13 May 2014. .
Tuberculosis (TB) is an infection that affects the lungs caused by an acid-fast bacillus M. tuberculosis (McCance, Huether, Brashers, & Rote, 2010, p. 1293). It is also considered as the leading cause of death from a curable infectious disease worldwide. It is highly contagious and the mode of transmission is by airborne droplets. A person can be exposed to the infection but not develop the illness, which is called latent TB infection. Unless the person is immunocompromised, some people remain asymptomatic until the disease is advanced. Signs and symptoms of TB includes fatigue, weight loss, lethargy, anorexia, and low grade fever that occurs in the afternoon. Diagnosis of the disease can be made through positive tuberculin skin test, sputum culture, immunoassays, and chest radiographs.
Tuberculosis (TB) is a transmittable and often severe airborne disease, an infection caused by a bacteria known as Mycobacterium tuberculosis (Mtb). TB usually affects the lungs, but it also can affect any other organ of the body. It is usually treatable with a scheduled routine of medicine taken for 6 months to 2 years, the length of treatment is conditional on the type and severity of the infection ( WHO. October 2015). This usually happens when a person breathes in the contaminated air, in which inhaled TB bacteria make their way to the lungs. The immune system cannot stop the bacteria from growing and spreading after the initial infection.
Untreated tuberculosis patients can pass the disease by coughing or sneezing, this fills the air with bacteria containing Mycobacterium. Inhaling these unhealthy bacteria a person can be infected with tuberculosis. “This causes the parasite to multiply in the blood, causing headaches, fever, weakness, pain in the joints, and stiffness.” (World Health Organization, 2014) People who become ill might not demonstrate signs of illness right away. Nevertheless, medication is available for tuberculosis, though this can take six to nine months and sometimes longer to be treated during the course of taking the
Mycobacterium tuberculosis is a nonmotile, acid-fast, obligate aerobe. The bacilli are 2-4 um in length and have a very slow generation time of between 15 and 20 hours. The cell wall of the mycobacterium is unique in that it is composed mainly of acidic waxes, specifically mycolic acids. M. tuberculosis is unusually resistant to drying and chemicals, contributing to the ease with which it is transmitted.
The disease can be caused by different mycobacterium such as Mycobacterium bovis, M. africanum, M. canettii, M. microti, and most commonly, M. tuberculosis; although the five are highly similar and are together termed the Mycobacterium tuberculosis complex (MTBC). Recently, two additional organisms. Mycobacterium pinnipedii and Mycobacterium caprae have also been implicated with the disease in humans. 6, 7 Members of the MTBC are gram-positive, long, rod-shaped bacterium with unique characteristics such as an exceptionally slow growth rate and a high content of lipids in their cell wall which provide protection against degradation and may account for their persistent survival in the environment even after the death of a host. 8
Tuberculosis has plagued mankind for a long time. This disease, which was previously believed to be eradicated, has once again shown up and begun attacking the lives of many humans. Tuberculosis infects a third of the population and kills a fraction of them. Many approaches have been used including different varieties of infection control, bodily defenses, and treatments to try to protect humans from tuberculosis. The best way to prevent tuberculosis infections is to contain the source of tuberculosis. The most common source of tuberculosis infection is from infected humans. By diagnosing, containing, and treating people with latent tuberculosis before they get active, contagious tuberculosis, tuberculosis can be quickly contained. Once someone has been diagnosed with TB, they should be placed under isolation.