Pharmacology

Tuberculosis

A Comprehensive Article

Infections

Tuberculosis (TB) is a chronic bacterial infection caused by Mycobacterium tuberculosis, primarily affecting the lungs (pulmonary TB) but capable of disseminating to other organs. In Ghana, TB remains a significant public health concern, especially among individuals with HIV, requiring early diagnosis and a standardized treatment regimen to prevent resistance and transmission.

๐Ÿฆ  Overview and Pathophysiology

TB spreads via airborne droplets and progresses from latent to active disease:

Causes

  • Organism: Mycobacterium tuberculosis
  • Transmission: Inhaled droplet nuclei from coughing
  • Risk Factors: HIV co-infection, malnutrition, overcrowding

Types

  • Pulmonary TB: Most common, contagious
  • Extrapulmonary TB: Lymph nodes, bones, CNS
  • Key Point: Latent TB can reactivate in immunocompromised states

๐Ÿ” Clinical Presentation

Symptoms vary by site and disease stage:

Symptoms

Pulmonary: Persistent cough (>2-3 weeks), hemoptysis, night sweats, weight loss
Systemic: Fever, fatigue, anorexia
Extrapulmonary: Swollen lymph nodes, back pain (spinal TB), headache (CNS TB)

Signs

Respiratory: Crackles, reduced breath sounds
General: Cachexia, lymphadenopathy
Other: Spinal deformity (Pottโ€™s disease), neurological deficits (CNS involvement)

Red Flags:
  • Hemoptysis, respiratory distress
  • Neurological signs (e.g., seizures, coma)
  • Failure to improve after 2 months of treatment

๐Ÿงช Diagnosis

Confirm TB with microbiological and imaging evidence:

Investigations

First-Line: Sputum smear microscopy (ZN staining), GeneXpert MTB/RIF
Imaging: Chest X-ray (apical infiltrates, cavitation)
Culture: Mycobacterium culture (gold standard)
Supportive: HIV test, FBC, liver function tests

Clinical Insight: Treat presumptively if high suspicion and diagnostic delay; confirm with labs.

๐Ÿ’Š Treatment

Standardized regimen aims to cure and prevent resistance.

Non-Pharmacological

Isolation: Respiratory isolation for contagious cases
Nutrition: High-calorie diet to support recovery
Education: Counsel on adherence and infection control

First-Line Regimen (New Cases)

  • 2HRZE: Isoniazid (H) 5 mg/kg, Rifampicin (R) 10 mg/kg, Pyrazinamide (Z) 25 mg/kg, Ethambutol (E) 15 mg/kg daily for 2 months
  • 4HR: Isoniazid + Rifampicin daily for 4 months
  • Total: 6 months

Retreatment Regimen

  • 2HRZES: Add Streptomycin (S) 15 mg/kg daily for 2 months
  • 1HRZE: Continue for 1 month
  • 5HRE: Isoniazid, Rifampicin, Ethambutol for 5 months
  • Total: 8 months

HIV Co-Infection

  • Regimen: Same as above, ensure ART compatibility
  • Key Point: Start ART within 2-8 weeks of TB treatment
Important Notes:
  • Monitor for hepatotoxicity (H, R, Z) and optic neuritis (E)
  • DOTS (Directly Observed Treatment, Short-course) recommended
  • Refer drug-resistant cases (e.g., GeneXpert MDR-TB positive)

๐Ÿคฐ Special Populations

Adjust treatment based on age and condition:

Children

Dose: Weight-based, e.g., H 10 mg/kg, R 15 mg/kg
Focus: Monitor growth and adherence

Pregnancy

Safe Drugs: Isoniazid, Rifampicin, Ethambutol
Avoid: Streptomycin (ototoxicity risk to fetus)
Support: Vitamin B6 (25-50 mg/day) with Isoniazid

Note: Consult specialist for complex cases.

๐Ÿšจ Referral Criteria

Immediate Referral:
  • Suspected or confirmed drug-resistant TB
  • Severe extrapulmonary TB (e.g., CNS, spinal)
  • Adverse drug reactions or treatment failure

Refer to TB control program or tertiary facility.

๐Ÿง  Key Takeaways

  • โœ… Diagnose Early: Use GeneXpert and sputum tests
  • โœ… Standard Treatment: 6-month regimen (2HRZE/4HR)
  • โœ… Adherence: Use DOTS to prevent resistance
  • โœ… Monitor: Liver function, vision, and response
  • โœ… Special Care: Adjust for children and pregnancy
  • โœ… Refer: For resistance or complications