Tuberculosis (TB)

Content of this page :

  1. Introduction
  2. Physiological Overview
  3. Symptoms 
  4. Treatment 

Introduction

Tuberculosis (TB) is an infection caused by M. tuberculosis, an acid-fast bacillus that usually affects the lungs but may invade other body systems. TB is the leading cause of death from a curable infectious disease throughout the world. TB cases increased greatly during the mid-1990s because of AIDS.
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Physiological Overview

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs (pulmonary TB), but it can also involve other parts of the body (extrapulmonary TB). Here’s a physiological overview of tuberculosis:

1. Transmission and Infection

  • Transmission: TB is spread through the air when an infected person coughs, sneezes, or speaks, releasing bacteria-containing droplets into the air.
  • Infection: When these droplets are inhaled, the bacteria can settle in the lungs and begin to multiply. The immune system may contain the infection by forming a granuloma (tubercle) around the bacteria.

2. Pathogenesis

  • Granuloma Formation: The immune response walls off the bacteria into granulomas, which contain infected macrophages, lymphocytes, and fibroblasts.
  • Latent TB vs. Active TB: In latent TB infection, the bacteria are dormant and do not cause symptoms. In active TB disease, the bacteria become active, causing symptoms and potentially spreading to other parts of the body.

3. Clinical Manifestations

  • Pulmonary TB: Symptoms include persistent cough (often with blood-tinged sputum), chest pain, weakness, weight loss, fever, and night sweats.
  • Extrapulmonary TB: TB can affect other organs such as the lymph nodes, kidneys, spine, and brain, leading to symptoms related to the affected organ.

4. Diagnosis

  • Tuberculin Skin Test (TST) or Interferon-Gamma Release Assays (IGRAs): Used to detect latent TB infection.
  • Chest X-ray: To detect abnormalities in the lungs suggestive of TB.
  • Sputum Smear and Culture: Microscopic examination and culture of sputum to confirm the presence of Mycobacterium tuberculosis.

5. Treatment

  • Antibiotic Therapy: Treatment typically involves a combination of antibiotics (e.g., isoniazid, rifampicin, pyrazinamide, ethambutol) for several months to eradicate the bacteria.
  • Directly Observed Therapy (DOT): Ensures patients take their medications consistently to prevent drug resistance and treatment failure.

6. Complications

  • Drug-Resistant TB: Some strains of M. tuberculosis have developed resistance to multiple antibiotics, making treatment more challenging.
  • Disseminated TB: In severe cases, TB can spread throughout the body, leading to life-threatening complications.
  • Miliary TB: TB that spreads widely in the body, causing tiny lesions (miliary nodules) in multiple organs.

7. Prevention

  • Vaccination: Bacillus Calmette-Guérin (BCG) vaccine is used in some countries to prevent severe forms of TB in children.
  • Infection Control: Ensuring proper ventilation, respiratory precautions, and early detection and treatment of active TB cases.

8. Global Impact

  • Public Health Measures: TB remains a significant global health burden, especially in developing countries with limited healthcare resources.
  • Multidrug-Resistant TB (MDR-TB): The emergence of drug-resistant strains poses challenges to TB control efforts worldwide.
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Symptoms

Tuberculosis (TB) can present with a variety of symptoms that may vary depending on whether the infection is pulmonary (affecting the lungs) or extrapulmonary (affecting other parts of the body). Here are the common symptoms of tuberculosis:

Pulmonary TB Symptoms:

  1. Persistent Cough: A cough that lasts for more than three weeks, often producing phlegm (sputum), which may be bloody.

  2. Chest Pain: Pain or discomfort in the chest, especially when breathing or coughing.

  3. Coughing up Blood: Hemoptysis, where there is blood in the sputum or coughed up from the lungs.

  4. Fatigue: Feeling tired or weak, sometimes accompanied by a lack of appetite and weight loss.

  5. Night Sweats: Profuse sweating, particularly during sleep, which may drench bedclothes.

  6. Fever: Low-grade fever that may be intermittent.

  7. Shortness of Breath: Particularly with exertion or as the disease progresses.

Extrapulmonary TB Symptoms:

  1. Lymph Node TB (Lymphadenitis): Swelling of lymph nodes, usually in the neck, armpit, or groin.

  2. Pleural TB: Infection of the lining around the lungs (pleura), causing chest pain and pleural effusion (fluid buildup).

  3. Genitourinary TB: Infection of the kidneys, bladder, or reproductive organs, presenting with symptoms like flank pain, painful urination, and blood in the urine.

  4. Skeletal TB: Infection of the bones and joints, causing pain, swelling, and limited movement.

  5. Meningeal TB: TB infection of the membranes covering the brain and spinal cord (meninges), leading to symptoms such as headache, stiff neck, and neurological deficits.

General Symptoms in Advanced or Severe TB Cases:

  1. Weakness: Generalized feeling of tiredness and lack of energy.

  2. Chills: Cold sensations, often accompanying fever.

  3. Loss of Appetite: Reduced desire to eat, leading to weight loss.

  4. Malaise: Overall feeling of being unwell.

Treatment

Treatment of tuberculosis (TB) typically involves a combination of antibiotics to eliminate the bacteria causing the infection. The exact treatment regimen depends on factors such as the type of TB (pulmonary or extrapulmonary), drug sensitivity of the bacteria, and the overall health of the patient. Here’s an overview of the treatment approach for TB:

1. First-Line Drugs (Standard Regimen)

The standard treatment for drug-susceptible TB involves a combination of four antibiotics, often referred to as the “first-line drugs”:

  • Isoniazid (INH): A key drug that kills actively dividing and dormant TB bacteria.
  • Rifampicin (RIF): Also effective against both actively dividing and dormant TB bacteria.
  • Pyrazinamide (PZA): Kills TB bacteria in acidic environments such as within cells.
  • Ethambutol (EMB): Prevents TB bacteria from forming cell walls, essential for their survival.

2. Treatment Regimen

  • Initial Phase (Intensive Phase): Typically lasts for 2 months and includes all four drugs (INH, RIF, PZA, EMB).
  • Continuation Phase (Consolidation Phase): Follows the initial phase and lasts for 4-7 months, focusing on INH and RIF.

3. Directly Observed Therapy (DOT)

  • Ensures Adherence: Healthcare workers or trained individuals observe patients taking their medications to ensure compliance and prevent drug resistance.

4. Monitoring and Follow-Up

  • Regular Monitoring: Monitoring for side effects and effectiveness of treatment through clinical evaluation, sputum smear and culture tests, and imaging (chest X-ray).
  • Adjustments: Treatment may be adjusted based on drug sensitivity testing or if adverse reactions occur.

5. Drug-Resistant TB

  • Multidrug-Resistant TB (MDR-TB): Resistant to at least INH and RIF. Requires treatment with second-line drugs, which are less effective, more toxic, and require longer treatment durations.
  • Extensively Drug-Resistant TB (XDR-TB): Resistant to INH, RIF, and fluoroquinolones, plus at least one of the injectable second-line drugs (e.g., amikacin, kanamycin).

6. Supportive Care

  • Management of Side Effects: Monitoring and managing potential side effects of medications, such as liver toxicity, peripheral neuropathy, and visual disturbances.
  • Nutritional Support: Ensuring adequate nutrition to support recovery and prevent malnutrition.

7. Public Health Measures

  • Contact Investigation: Identifying and screening individuals who have been in close contact with TB patients to prevent further spread of the disease.
  • Infection Control: Ensuring proper ventilation in healthcare settings and use of personal protective equipment (PPE) to minimize transmission.

8. Completion of Treatment

  • Importance of Completion: It’s crucial for patients to complete the full course of treatment as prescribed, even if they start feeling better. This helps prevent relapse and the development of drug resistance.

9. Prevention

  • BCG Vaccine: Vaccination in some countries to prevent severe forms of TB, particularly in children.
  • TB Screening: Identifying and treating latent TB infection to prevent progression to active disease.
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