Tuberculosis

Tuberculosis is an infectious disease caused by the organism Mycobacterium tuberculosis. Unlike most other bacteria, M. Tuberculosis is surrounded by an outer capsule that makes the organism very resistant to destruction.

Globally, 2 billion people are infected and 2 million to 3 million people die from TB each year.

It can produce silent, latent infection as well as progressive, active disease.

Mycobacterium tuberculosis is primarily transmitted via the airborne route.

Human immunodeficiency virus (HIV) is the most important risk factor for active TB

Primary infection is initiated by the alveolar implantation of organisms in droplet nuclei that are small enough (1 to 5 mm) to escape the ciliary epithelial cells of the upper respiratory tract and reach the alveolar surface.

Once implanted, the organisms multiply and are ingested by pulmonary macrophages, where they are killed, or, they continue to multiply.

With bacterial multiplication, the macrophages eventually rupture, releasing many bacilli.

The primary lesion that results in the lung during tuberculosis Infection is called the Ghon’s focus . If the lesion also involves regional lymph nodes, it is termed a Ghon’s complex

Necrosis of infected lung tissues may result in a cheesy appearance to the tissue that is referred to as a caseous necrosis. Liquefaction of the necrotic lesions might also occur over time

In an otherwise healthy individual, the immune system is usually able to contain the organism and over time will encapsulate it through calcification of the lesions.

These calcified Ghon’s complexes are readily visualized by chest radiograph for the remainder of the patient’s life .

 Because live M. tuberculosis is often found within

these encapsulations, impairment of immune function in the infected individual may lead to reactivation of the primary infection.

Testing for TuberculosisMantoux method test — Intradermal test for reaction

against the tuberculin purified protein derivative standard (PPDS)

(tuberculin skin test)

Chest radiograph to identify Ghon’s complex

When active TB is suspected, attempts should be made to isolate M. tuberculosis from the infected site. Daily sputum collection over 3 consecutive days is recommended.

Manifestations of primary tuberculosis:• Productive, prolonged cough• Chest pain, hemoptysis• Chill, fever, night sweats• Anorexia, weight loss

Treatment of tuberculosis

Despite a continuous decline in the incidence of tuberculosis in the decades preceding the 1980s, since 1985 there has been a steady increase in the worldwide incidence of tuberculosis. A major contributing factor to this resurgence of tuberculosis has been the spread of HIV.

Mycobacterium tuberculosis can be a opportunistic organism that infects AIDS patients whose immune systems are weakened and inadequate to combat the organism.

The rise of homelessness may also be a contributing factor to increased rates of tuberculosis in urban settings, as the organism grows in the dark, moist environments in which homeless people sometimes dwell.

Management of tuberculosis often requires prolonged Treatment with powerful antimycobacterial drugs

Unfortunately, in recent years the treatment of tuberculosis has been complicated by the rise of organisms that are resistant to one or more of the commonly used antitubercular agents.

In cases of multidrugresistant tuberculosis, mortality can be on then order of 70 to 90%.

Factors that affect immune function such as proper nutrition and management of other Diseases are also essential for successful treatment of tuberculosis.

 

Drugs for the Treatment of Tuberculosis

Isoniazid Rifampicin

Ethambutol

Thank You