General Overview of Tuberculosis: Causes, Effects, and Treatment

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. Tuberculosis spreads by respiratory droplets exhaled by infected people. There are two forms of tuberculosis: latent TB and active TB. A person infected with latent TB will be a carrier of a dormant form of the bacteria but will show no clinical manifestations of the infection. Tuberculosis is the leading cause of death from infectious diseases and the foremost reason of death among people who have been infected with HIV. For example, someone with a strong immune system would be able to effectively fight off the bacterial infection. But those infected with HIV will not be able to effectively kill the infection. Two billion people in the world are infected with tuberculosis. The following are regions of the world that have the highest incidence of tuberculosis: Southeast Asia, Africa, and Western Pacific. There is an antibiotic regimen (Isoniazid) that an infected person can take that will treat a tuberculosis infection. It is important that the patient takes the medication as prescribed. If not, it may cause antibiotic resistance or not kill all of the bacteria thus causing a resurgence of the tuberculosis infection.

Etiology and Risk Factors

The cause of tuberculosis is a bacteria named Mycobacterium tuberculosis. It is spread from person to person by inhalation of airborne droplets that are released when a person with active tuberculosis coughs, talks, or sneezes. Mycobacterium tuberculosis is gram-positive bacteria that requires oxygen to survive. Airborne droplets can be transferred from a person with active tuberculosis through the air and can actually linger for long periods of time. Risk factors include the following: living in close quarters with an infected person, poor ventilated rooms, crowded living conditions, homelessness, living in a long-term care facility, and living in a third world country that has a high incidence of tuberculosis. Infants and young children have a higher risk of developing active tuberculosis than adults. There is a difference in the most common mode of transmission between adults and children. Children contract tuberculosis infections through their community or the adults who they directly come into contact with. The activation of the latent form of tuberculosis into the active form in children is very uncommon in children who are younger than 10 years old. Children are usually found to show no symptoms of tuberculosis despite an abnormal chest X-ray. Children who have active tuberculosis are also found to be less contagious than adults because they do not cough as much and are therefore not spreading many airborne droplets. Human leukocyte antigen (HLA) genes put people at higher risk of tuberculosis infection.

Pathophysiological Processes

The pathophysiological onset of tuberculosis starts in the respiratory system. When primary infection of tuberculosis takes place, Mycobacterium tuberculosis bacilli are rapidly reproducing within alveolar macrophages, which are subsequently spread through the lymphatic system via lymph vessels. This process induces the first inflammatory response and causes caseous necrosis and granulomatous lesions (tubercles) to form in the lungs. These lesions can heal which cause calcified granulomas to form but a weak immune system may not be able to kill all of the infection causing active tuberculosis to manifest.

Clinical Manifestations & Complications

The following are the most indicative signs and symptoms of tuberculosis: fatigue, weakness, loss of appetite, weight loss, night sweats, fever, and chills. More symptoms include: purulent or bloody sputum, dyspnea, chest pain, and a persistent cough that lasts longer than three weeks. There are few complications associated with tuberculosis. Complications include osteomyelitis, hydrocephalus, pleural effusion, respiratory failure, brain ischemia, or multiple organs infected by tuberculosis. If left untreated, tuberculosis can cause permanent lung damage and spread to multiple organs. Diagnostics Diagnosis of tuberculosis starts by conducting a few tests and obtaining their results. Laboratory tests and diagnostic imaging are just a few examples how tuberculosis can be diagnosed. A very common test that is used to diagnose tuberculosis is the tuberculin skin testing (TST) that uses a purified protein derivative (PPD) that is injected right underneath the skin. A positive TST includes the finding of a swelled bump that formed over the area of injection that is greater or equal to 5 mm 48-72 hours after injection of the PPD. Chest X-rays can also be used to diagnose tuberculosis. An X-ray can reveal any necrotic tissue or granulomatous lesions (tubercles) formations in the chest, indicating active tuberculosis. A chest X-ray can also show enlarged hilar lymph nodes, lung nodules, atelectasis, or lung tissue cavitation – which are all indications of a tuberculosis infection. Acid-fast sputum (AFB) sputum cultures and smears identify mycobacteria which are typically rod-shaped bacilli.

Conclusion

Tuberculosis or TB is caused by a bacterial infection. Those who have contracted tuberculosis latent or active were infected by droplet of someone who had active TB. Tuberculosis is treatable and if caught at the onset of symptoms will not cause permanent damage to the individual. Diagnostic tests can be used to confirm a suspicion of TB. Adherence to antibiotic treatment is essential to the treatment of TB.