PULMONARY TUBERCULOSIS

• Tuberculosis (TB) is an infectious disease that primarily affects the lung parenchyma. • It also may be transmitted to other parts of the body, including the

meninges, kidneys, bones, and lymph nodes.

Causative agent• Mycobacterium tuberculosis

• Mycobacterium bovis and Mycobacterium avium have rarely been associated with the development of a TB infection.

Risk factors• Close contact with someone who has active TB. • Immunocompromised status (eg, those with HIV infection, cancer,

transplanted organs, and prolonged high-dose corticosteroid therapy) • Substance abuse (IV or injection drug users and alcoholics) • Any person without adequate health care • Preexisting medical conditions or special treatment (eg, diabetes,

chronic renal failure, malnourishment, selected malignancies, hemodialysis, transplanted organ, gastrectomy, or jejunoileal bypass)

• Immigration from countries with a high prevalence of TB • Institutionalization (eg, long-term care facilities, psychiatric

institutions, prisons) • Living in overcrowded, substandard housing • health care workers

Transmission• TB spreads from person to person by airborne transmission• An infected person releases droplet nuclei (generally particles 1 to

5micrometers in diameter) through talking, coughing, sneezing, laughing, or singing. Larger droplets settle; smaller droplets remain suspended in the air and are inhaled by the susceptible person.

Pathophysiology Person inhales mycobacterium bacilli

Bacteria transmitted to the alveoli

Bacteria are deposited and multiply + Transported to other parts of the body

The body’s immune system responds by initiating an inflammatory reaction.

Phagocytes (neutrophils and macrophages) engulf many of the bacteria, and TB-

specific lymphocytes lyse (destroy) the bacilli and normal tissue.

Formation of exudate in the alveoli, causing bronchopneumonia.

• The initial infection usually occurs 2 to 10 weeks after exposure.

Granulomas form (new tissue masses of live and dead bacilli)

it is surrounded by macrophages, which form a protective wall

Granulomas are then transformed to a fibrous tissue mass, the central portion

of which is called a Ghon tubercle.

The material becomes necrotic, forming a cheesy mass.

This mass may become calcified and form a collagenous scar.

The bacteria become dormant, there is no further progression of active disease.

• After initial exposure and infection, the person may develop active disease because of a compromised or inadequate immune system response. • Active disease also may occur with reinfection and activation of

dormant bacteria.

The Ghon tubercle ulcerates, releasing the cheesy material into the bronchi.

The bacteria become airborne, resulting in further spread of the disease.

The ulcerated tubercle heals and forms scar tissue.

The infected lung become more inflamed

Further development of bronchopneumonia and tubercle formation.

Clinical Manifestations• low-grade fever• Cough – non-productive or mucopurulent • night sweats• Fatigue• weight loss. • Hemoptysis • Anorexia

PULMONARY SYMPTOMS • Dyspnea • Non resolving bronchopneumonia • Chest tightness • Non productive cough • Mucopurulent sputum with hemoptpysis • Chest pain

Assessment and Diagnostic Findings• tuberculin skin test• chest x-ray• acid-fast bacillus smear• sputum culture • Biopsy• Bronchoscopy• Chest CT scan• Interferon-gamma release blood test such as the QFT-Gold test-

• QFT-Gold test measures interferon-gamma in the testee's blood after incubating the blood with specific antigens from M. Tuberculosis proteins

CLASSIFICATION OF TB• Class 0: no exposure; no infection • Class 1: exposure; no evidence of infection • Class 2: latent infection; no disease (eg, positive PPD reaction but no

clinical evidence of active TB) • Class 3: disease; clinically active • Class 4: disease; not clinically active • Class 5: suspected disease; diagnosis pending

Management • PULMONARY TB is treated primarily with antituberculosis agents for 6

to 12 months.• First line antitubercular medications • Streptomycin 15mg/kg • Isoniazid or INH(Nydrazid) 5 mg/kg(300 mg max perday) • Rifampin 10 mg/kg • Pyrazinamide 15 – 30 mg/kg • Ethambutol(Myambutol) 15 -25 mg/kg daily for 8 weeks and continuing for up

to 4 to 7 months

• Second line medications • Capreomycin 12 -15 mg/kg • Ethionamide 15mg/kg • Paraaminosalycilate sodium 200 300 mg/kg • Cycloserine 15 mg/kg

• Recommended treatment guidelines - multiple-medication regimen of INH, rifampin, pyrazinamide, and either streptomycin or ethambutol. • administered daily for 8 weeks. • If cultures demonstrate that the organism is sensitive to the medications before the 8

weeks of therapy have been completed, either ethambutol or streptomycin can be discontinued. • After 8 weeks of this medication regimen, pyrazinamide can be discontinued and INH

and rifampin are administered for an additional 4 months. • A person is considered noninfectious after 2 to 3 weeks of continuous medication

therapy. • Vitamin B (pyridoxine) is usually administered with INH to prevent INH-associated

peripheral neuropathy

Complications • Bones - Spinal pain and joint destruction may result from TB (TB spine

or potss spine) • Brain(meningitis) • Liver or kidneys – military TB• Heart(cardiac tamponade) • Pleural effusion • Tb pneumonia • Serious reactions to drug therapy(hepato toxicity;hypersentivity)