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Tuberculosis

Tuberculosis is a highly communicable disease caused by Mycobacterium tuberculosis. Mycobacterium tuberculosis is a nonmotile, nonsporulating, acid-fast rod that secrets niacin, and when the bacillus reaches a susceptible site, it multiplies freely.

Because M. tuberculosis is an aerobic bacterium, it primarily affects the pulmonary system, especially the upper lobes where the oxygen content is greatest, but also can affect other areas of the body, such as the brain, intestines, peritoneum, kidney, joints and liver.

A multidrug-resistant strain of tuberculosis can exist as a result of improper of noncompliant use of treatment programs and the development of mutations in the tubercle bacilli. The goal of treatment is to prevent transmission, control symptoms, and prevent progression of the disease.

Transmission

TuberculosisThe transmission of tuberculosis is via airborne route by droplet infection. When infected individual coughs, laughs, sneezes, or sings, droplet nuclei containing tuberculosis bacteria enter the air and may be inhaled by others. Identification of those individuals in close contact with the infected individual is important so that they can be tested and treated as necessary. When contacts have been identified, these persons are assessed with a tuberculin test and chest x-ray films to determine infection with tuberculosis. After the infected individual has received tuberculosis medication for 2 to 3 weeks, the risk of transmission is reduced greatly.

Signs and Symptoms

· Can be asymptomatic in primary infection

· Lethargy

· Fatigue

· Anorexia

· Weight loss

· Low-grade fever

· Chills

· Night sweats

· Persistent cough and production of mucoid and mucopurulent sputum, which is occasionally blood streaked

· Chest tightness and dull, aching chest pain may accompany the cough

Diagnostic Tests

· Chest assessment

A physical examination of the chest does not provide conclusive evidence of tuberculosis. Chest x-ray film is not definitive, but the presence of mutli-nodular infiltrates with calcification in the upper lobes suggests tuberculosis.

· Sputum cultures

Sputum specimens are obtained for an acid-fast smear. A sputum culture identifying M. tuberculosis confirms the diagnosis. After medications are started, sputum samples are obtained again to determine the effectiveness of therapy. Most clients have negative cultures after 3 months of treatment.

· Mantoux test

The mantoux test is the most reliable determinant of infection with tuberculosis. A positive reaction does not mean that active disease is present but indicates exposure to tuberculosis or the presence of inactive disease. Once the test is positive, it will be positive in any future tests.

A 0.1 ml of intermediate strength purified protein derivative containing 5 tuberculin units is administered intradermally in the forearm. An area of induration measuring 10mm or more in diameter after 72 hours after injection indicates that the individual has been exposed to tuberculosis.

Disease progression

Droplets enter the lungs and the bacteria form a tubercle lesion. The defense systems of the body encapsulate the tubercle leaving a scar. If encapsulation does not occur, bacteria may enter the lymph system, travel to the lymph nodes, and cause an inflammatory response called granulomatous inflammation. Primary lesions form and the primary lesions can become dormant but can be reactivated and become a secondary infection when reexposed to the bacterium.

In an active phase, tuberculosis can cause necrosis and cavitation in the lesions, leading to rupture and the spread of necrotic tissue and damage to various parts of the body.

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