Tuberculosis (TB)

• Tuberculosis is a potentially severe infectious disease primarily affecting the lungs (pulmonary TB) but can also affect other parts of the body (extrapulmonary TB).
• It is caused by the bacterium Mycobacterium tuberculosis.

Signs and Symptoms of Tuberculosis

1. Pulmonary TB:

   • Persistent Cough: Lasting more than three weeks, sometimes producing blood (hemoptysis).
   • Chest Pain: Painful breathing or coughing.
   • Fever and Chills: Often in the evening.
   • Night Sweats: Profuse sweating at night.
   • Weight Loss: Unintended weight loss and loss of appetite.
   • Fatigue: Persistent tiredness and weakness.

2. Extrapulmonary TB:

   • Lymphadenitis: Swollen lymph nodes.
   • Meningitis: TB infection of the brain lining, causing headaches, fever, and neurological symptoms.
   • Skeletal TB: Affects bones and joints, leading to pain and swelling.
   • Genitourinary TB: Involving kidneys, bladder, or reproductive organs.
   • Miliary TB: Disseminated TB affecting multiple organs.

Types of Tuberculosis

1. Based on Disease Location:

   • Pulmonary TB: Affects the lungs.
   • Extrapulmonary TB: Affects organs other than the lungs.

2. Based on Drug Resistance:

   • Drug-Sensitive TB: Responds to standard anti-TB drugs.
   • Multidrug-Resistant TB (MDR-TB): Resistant to at least isoniazid and rifampicin.
   • Extensively Drug-Resistant TB (XDR-TB): Resistant to isoniazid, rifampicin, any fluoroquinolone, and at least one second-line injectable drug.

Etiology of Tuberculosis

• Causative Agent: Mycobacterium tuberculosis.
• Transmission: Airborne, through inhalation of droplet nuclei from a person with active pulmonary TB.

Pathogenesis of Tuberculosis

1. Primary Infection:

   • Inhalation: tuberculosis enters the lungs.
   • Phagocytosis: Alveolar macrophages ingest bacteria, which survive and multiply inside macrophages.
   • Formation of Granulomas: Immune response forms granulomas to contain the infection, leading to latent TB.

2. Reactivation:

   • Immune Compromise: Reactivation of latent TB occurs when the immune system is weakened.
   • Active TB: Bacteria multiply, causing tissue damage and symptomatic disease.

Treatment

1. Standard Regimen for Drug-Sensitive TB:

   • Intensive Phase: 2 months of isoniazid, rifampicin, pyrazinamide, and ethambutol.
   • Continuation Phase: 4 months of isoniazid and rifampicin.

2. MDR-TB Treatment:

   • Longer Duration: 18-24 months with second-line drugs like fluoroquinolones and injectable agents (kanamycin, amikacin).

3. XDR-TB Treatment:

   • Complex Regimens: Often include bedaquiline, linezolid, and other newer drugs, lasting up to 24 months or more.

Supportive Care:

• Nutritional Support: To counteract weight loss and malnutrition.
• Management of Side Effects: Regular monitoring and management of drug side effects.
• Isolation Measures: To prevent transmission until the patient is non-infectious.

Prevention of Tuberculosis:

• BCG Vaccine: Administered in infancy in endemic countries.
• Early Detection and Treatment: Active case finding, contact tracing, and treatment of latent TB.
• Infection Control: Use of personal protective equipment (PPE) and proper ventilation in healthcare settings.

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