Pathophysiology - Tuberculosis

Tuberculosis

• An acute or chronic infection caused by Mycobacterium tuberculosis
• An acid-fast aerobic bacterium is characterized by pulmonary infiltrates, formation of granulomas with caseation, fibrosis, and cavitation
• Drug resistant TB or atypical Mycobacterial disease

Incubation Period

4-8weeks

Mode of Transmission

• Inhalation
• Ingestion of inoculation of droplet nuclei, spread through respiratory route.
• Swallowing infected sputum may lead to laryngeal. Oropharyngeal, and intestinal tuberculosis

Schematic Diagram

Inhaled Mycobacterium Tuberculosis

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Organism multiply-survive URT

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Spread through the body: Alveoli (established infection)

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Lymphatic channels carry them to regional lymphnodes

Circulatory system transport them to distant tissues and organs

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The organism prefers body tissues with high oxygen concentration: upper lungs and kidneys

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The immune system attacks

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Macrophages engulf the organism

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Macrophages surround them and wall them off in tiny, hard capsules

(Tb organism can reside in these tubercles in dormant stage indefinitely)

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Immune system weakens

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Infection develops into active TB

(Tb reactivation)

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TB organism multiply stimulating the immune system

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Activate the Cytotixic lymphocyte macrophages

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Emission of toxins that liquefy and destroy lung tissue

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Immune response results to formation of cavities

Signs and Symptoms

• Malaise
• Pleuritic pain
• Easy fatigability
• Cough more than 3 weeks
• Low-grade fever
• Chills
• Night sweats
• Anorexia
• Unexplained weight loss
• Hemoptysis
• Hoarseness

Clinical Findings

• Chest X-ray reveals presence of active calcified lesions
• Tuberculin Testing: Mantoux test-involves the use of pure protein derivatives=redness and edema present 48-72 hours later indicate a positive finding
• AFB sputum specimen and sputum

Treatment

• Antitubercular therapy at least 6 months (after 2-4weeks-no longer infectious)
• Medications:
• Isoniazid (INH) – notable side effect of this drug is peripheral neuritis
• Rifampin (Rifampicin) – notable side effect of this drug is orange discoloration of urine and other secretions
• Pyrazinamide
• Ethambutol - notable side effect of this drug is optic neuritis
• Streptomycin – the first drug effective against TB

Nursing Consideration

• AFB Isolation precaution
• Respiratory precautions
• Health teachings include having adequate rest and a well balanced diet ( high in carbohydrate, protein)
• Constant monitoring of the side effects of the anti-TB drugs
• Observe proper technique to prevent spread of infection
• Emphasize the regular check-up schedule