Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis. It mainly affects the lungs but can involve any organ, including lymph nodes, bones, kidneys, and the brain. TB spreads through droplets when an infected person coughs or sneezes. Effective treatment requires multiple drugs over a long duration to prevent resistance and achieve a complete cure.
Types of Tuberculosis
- Pulmonary TB – affects the lungs
- Extrapulmonary TB – affects organs outside the lungs (e.g., lymph nodes, spine, meninges)
- Latent TB infection – bacteria are present but inactive; no symptoms
- Active TB – bacteria are multiplying and causing symptoms
Signs and Symptoms
- Chronic cough for more than 2–3 weeks
- Blood in sputum (hemoptysis)
- Unexplained fever
- Night sweats
- Weight loss and fatigue
- Loss of appetite
Extrapulmonary TB symptoms depend on the affected organ.
Diagnosis of TB
- Sputum smear microscopy – detects acid-fast bacilli
- CBNAAT / GeneXpert – identifies TB bacteria and rifampicin resistance
- Chest X-ray
- Tuberculin skin test (for screening)
- Culture – confirms diagnosis but takes longer
Treatment of Drug-Sensitive TB
Treatment involves a combination of four first-line drugs known as the RIPE regimen:
- R – Rifampicin
- I – Isoniazid
- P – Pyrazinamide
- E – Ethambutol
Standard Treatment Regimen
- Intensive Phase (2 months): HRZE daily
- Continuation Phase (4 months): HR daily
Total duration: 6 months for uncomplicated pulmonary TB.
Mechanism of Action of First-Line Drugs
- Isoniazid: Stops mycolic acid synthesis (cell wall)
- Rifampicin: Inhibits RNA polymerase
- Pyrazinamide: Works in acidic environments inside macrophages
- Ethambutol: Inhibits arabinogalactan synthesis (cell wall)
Common Side Effects of Anti-TB Drugs
- Isoniazid: Peripheral neuropathy (prevented by pyridoxine), hepatotoxicity
- Rifampicin: Orange-colored urine/tears, liver toxicity, drug interactions
- Pyrazinamide: Joint pain, hyperuricemia, hepatotoxicity
- Ethambutol: Optic neuritis (blurred vision, red-green color blindness)
Drug-Resistant Tuberculosis
- MDR-TB: Resistant to isoniazid and rifampicin
- XDR-TB: MDR-TB with additional resistance to fluoroquinolones and injectable agents
Treatment of MDR-TB
Includes second-line drugs such as:
- Fluoroquinolones (moxifloxacin, levofloxacin)
- Bedaquiline
- Linezolid
- Clofazimine
- Cycloserine
Treatment duration ranges from 9 to 20 months depending on the regimen.
TB in Special Situations
1. TB in Pregnancy
- Most first-line drugs are safe
- Streptomycin is avoided due to fetal ototoxicity
2. TB with HIV
- Start TB treatment immediately
- Start ART within 2 weeks for severe TB
- Monitor for drug interactions, especially rifampicin
3. TB in Children
- Diagnosis is challenging due to low sputum production
- Weight-based dosing required
Patient Counseling Tips
- Complete the full course even if symptoms improve early
- Take medicines at the same time every day
- Avoid alcohol (risk of liver toxicity)
- Report vision changes immediately (ethambutol)
- Do not skip doses to avoid resistance
Detailed Notes:
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