Professor Ray Ramirez
December 5, 2014
Tuberculosis: Leading Disease Killer in the World
Microbes orbit the world that is around us involving being in the air and on surfaces we may come in close contact with. In the medical terms, microbiology involves the study of microscopic organisms, bacteria, archaea, fungi, protozoa, algae, and multi cellular animal parasites (Baumann 3-5). It is important that we acquire knowledge of these subjects because there are many infectious diseases that can directly and indirectly affect our immediate environment and our family. Common bacterial diseases of the lower respiratory system include bacterial pneumonias, legionnaires’ disease, pertussis (whooping cough) and tuberculosis (TB) (VanMeter 219). When working in the medical setting, TB is a disease taken quite seriously due its etiology, pathophysiology, risk factors, and mortality rate.
TB is caused by mycobacterium tuberculosis (Mtb). This is a gram positive rod consisting of cell walls that are thick and contain peptidoglycan with abundant mycolic acid. Gram positive bacteria have cell walls with up to sixty percent mycolic acid (Baumann 65).This is a waxy lipid directly responsible for many unique characteristics of Mtb and other mycobacteria (Baumann 691). The mycolic acid assists these cells in surviving dessication which make it difficult to strain with regular water based dyes (Baumann 65). Mtb is small, slow growing and it can only live inside of people. It is also aerobic, so it needs oxygen to survive (NIH 1).
When a person breathes in contaminated air, inhaled bacteria reaches the lungs. This is when Mtb infection begins, however, not everyone infected gets sick. This disease can be dormant for years and not cause disease that in turn will become latent. Individuals that have latent infections will not get sick but some will eventually get the disease (NIH1). There is about five percent to ten percent of infected people who don’t get treatment for latent disease and TB will develop later in life (CDC 1). Active TB disease is caused when bacteria actually reaches the lungs and cause the Mtb infection. The immune system will not be able to stop the TB from growing and spreading after initial infection (NIH1). TB can infect other parts of the body as well, such as kidneys, spine, and brain (Mayo 3).
Pathophysiology consists when Mycobacterium is inhaled via inhaling of infectious respiratory droplets from people that are infected (Baumann 692). Alveoli consist of macrophages and they will try to phagocytize mycobacteria. Instead, macrophages are unable to digest them, so the bacteria will replicate inside and kill phagocytes. Bacteria is then released from dead macrophages and then phagocytized by other macrophages. After this happens, cycle starts all over again. Infected macrophages present antigen to T lymphocytes that produce lymphokines attraction and activating more macrophages. They also cause inflammation of lung tissue. Macrophages then surround site of infection and it forms a tubercle. The tubercle will last two to three months period (Baumann 693).Once the tubercle is formed, other cells deposit collagen fibers that enclose infected macrophages and lungs cells inside tubercle. Infected cells die which will release Mtb and produce dead tissue. This tissue is known as necrotic tissue (Baumann 693).
Common risk factors generally fall into two catergories. These are people who have just been infected with Mtb and people with weak immune systems due to certain medical conditions. In regards to recently infected individuals, a person can become infected by being in close contact with others via areas of the world, facilities housing TB patients, and children that have a positive TB test under five years of age. (CDC 1). A person can also contract the disease by living in or traveling to countries that have high rate of TB such as Sub- Saharan Africa, India, China, Russia, and...
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