Mycobacterium tuberculosis is an aerobic, slow-growing, acid-fast bacillus (AFB). Its waxy mycolic acid cell wall is responsible for acid-fast staining and resistance to desiccation and many disinfectants.
Initial infection in a naive host. Ghon focus forms in mid-zone of lung. Most cases asymptomatic — immune system contains bacilli in a granuloma (caseating). Leads to LTBI in 90% of cases.
Reactivation of dormant bacilli — triggered by immunosuppression (HIV, DM, steroids, TNF-alpha inhibitors, malnutrition). Affects upper lobes preferentially. More cavitation, more infectious.
| Feature | Active TB | LTBI |
|---|---|---|
| Infectious? | YES — can transmit | NO — not infectious |
| Symptoms | Cough, fever, weight loss, sweats | NONE — asymptomatic |
| CXR | Abnormal (consolidation/cavitation) | Normal |
| Sputum AFB | Positive (if pulmonary) | Negative |
| TST / IGRA | Positive | Positive |
| Treatment | Full 6-month RIPE regimen | Preventive therapy (6H or 3HR) |
| Notification | Mandatory (all GCC countries) | Not required (varies) |
Constitutional symptoms (night sweats, weight loss, fever) are classic but non-specific. Pulmonary TB must be suspected in any patient with cough >3 weeks from a high-prevalence country.
GCC countries host millions of migrant workers from South Asia (India, Pakistan, Bangladesh, Nepal) and Africa — regions with very high TB burden. TB notification is mandatory in all GCC countries. Pre-employment medical examinations require a chest X-ray for all expatriate workers.
Screening is conducted at government-approved medical centres. Workers with active TB are referred for treatment before or instead of entry.
MDR-TB: resistant to both isoniazid AND rifampicin — two most powerful first-line drugs.
XDR-TB: MDR-TB PLUS resistance to fluoroquinolone AND at least one injectable second-line drug.
GCC treatment follows WHO/national protocols — specialised centres manage MDR/XDR cases. Bedaquiline-based regimens now first-line for MDR-TB.
Sputum collection safety: Collect in outdoor or well-ventilated area — NEVER in a corridor, toilet, or enclosed ward room. Provide patient with labelled container and clear instructions for early morning specimen.
TST does NOT distinguish active TB from LTBI. A positive TST means TB infection — further investigation required to rule out active disease.
Blood test — measures IFN-gamma release from T-lymphocytes when stimulated by M.tb-specific antigens (ESAT-6, CFP-10). These antigens are NOT in BCG or most NTM, so:
IGRA preferred over TST in BCG-vaccinated individuals — no false positives from BCG. This is critical in GCC populations where BCG is universal.
Indicated when sputum AFB negative and strong clinical suspicion — smear-negative TB. Bronchoalveolar lavage (BAL) sent for:
Post-bronchoscopy: isolate patient pending results — procedure can aerosolise bacilli.
All expatriate workers applying for GCC work visas require a chest X-ray at an approved medical centre. Active TB = visa denial and repatriation. LTBI management varies by country — some require treatment completion before visa approval.
Regimen notation: Number = months. Letters = drugs. 2HRZE = 2 months of Isoniazid + Rifampicin + Pyrazinamide + Ethambutol. 4HR = 4 months of Isoniazid + Rifampicin only.
Goal: rapid bactericidal effect — reduce bacillary load, prevent emergence of resistance. Sputum conversion expected by 2 months.
Goal: sterilising phase — eliminate dormant bacilli, prevent relapse. Total duration = 6 months for drug-sensitive pulmonary TB.
TB meningitis and bone TB: extended to 12 months total. Miliary TB: 6–9 months.
DOT is the cornerstone of TB treatment adherence. A trained healthcare worker (or designated observer) watches the patient swallow every dose.
MDR-TB: Resistant to isoniazid AND rifampicin
Treatment: 18–24 months. WHO BPaL regimen: Bedaquiline + Pretomanid + Linezolid now preferred for eligible patients. Specialised TB centre required. All MDR-TB cases must be notified to national TB programme.
| Drug | Key Side Effects | Monitoring | Action if Toxicity |
|---|---|---|---|
| Rifampicin (R) | Orange urine/secretions, hepatotoxicity, flu-like syndrome, thrombocytopaenia | LFTs monthly (baseline + monthly); FBC | Stop if jaundice; warn patient orange urine is normal |
| Isoniazid (H) | Peripheral neuropathy, hepatotoxicity, psychosis, seizures | LFTs; give Pyridoxine B6 with every dose | Stop if jaundice or neuropathy; B6 is protective |
| Pyrazinamide (Z) | Hepatotoxicity, hyperuricaemia (gout), arthralgia, rash | LFTs; uric acid; joint pain assessment | Stop if jaundice; manage gout with allopurinol if needed |
| Ethambutol (E) | Optic neuritis — reduced visual acuity and colour vision (red-green) | Monthly visual acuity + colour vision (Ishihara) | STOP immediately if visual changes; usually reversible if caught early |
Drug-Induced Liver Injury (DILI) Threshold: AST or ALT >3× upper limit of normal WITH symptoms (jaundice, nausea, abdominal pain) = STOP all hepatotoxic drugs (H + R + Z). Senior review urgently.
Rifampicin Drug Interactions: Potent CYP450 inducer — reduces efficacy of oral contraceptives (advise barrier method), antiretrovirals, warfarin, corticosteroids, methadone, and many others. Always check drug interactions.
Click each day to mark dose as observed. Shift+click to mark as missed.
TB is spread exclusively by airborne transmission — infectious patients generate droplet nuclei (<5 μm) when coughing, sneezing, singing, or speaking. These particles:
Laryngeal TB is the most infectious form — patient effectively coughs TB into the air with every word.
N95 respirator (FFP2/FFP3) — NOT a surgical mask. N95 filters 95% of particles ≥0.3 μm. Must be fit-tested annually in GCC hospitals.
All THREE criteria must be met:
Culture positivity may continue — smear negativity is the key discharge-from-isolation criterion.
Nurses play a key advocacy role for migrant workers diagnosed with TB. Understand deportation protocols (active TB = potential repatriation in most GCC states) and ensure patients receive:
HIV infection increases TB risk approximately 20-fold. TB is the leading cause of death in HIV-positive patients globally. All TB patients should be tested for HIV.
IRIS (Immune Reconstitution Inflammatory Syndrome): Paradoxical worsening of TB symptoms after starting ART — the recovering immune system mounts an excessive response. Managed with corticosteroids if severe. Do NOT stop ART or TB treatment.
Untreated TB in pregnancy carries significant risk of preterm delivery, low birth weight, and vertical transmission. Treatment is more dangerous to withhold than to give.
Rifampicin and isoniazid are present in breast milk at sub-therapeutic levels — breastfeeding is safe. Give infant isoniazid prophylaxis if mother smear-positive at delivery. BCG vaccination of neonate after isoniazid prophylaxis completed.
Children rarely produce adequate sputum — diagnosis relies on contact history, TST/IGRA, CXR, and clinical features. Children are almost always a contact of an adult case.
Diabetes mellitus increases TB risk approximately 3-fold and is associated with:
Bidirectional relationship: TB also worsens glycaemic control. Essential nursing actions: monitor blood glucose closely during TB treatment; rifampicin affects sulphonylurea metabolism; coordinate endocrinology review.
GCC context: very high DM prevalence in Gulf nationals (30–40%) — DM-TB co-morbidity is clinically very common in this region.
TB meningitis (TBM) has the highest mortality and morbidity of all TB forms. Caused by haematogenous spread to meninges.
TB of the vertebral bodies — most common at thoracolumbar junction (T10–L2). Vertebral body destruction leads to collapse, gibbus deformity, and potentially paraplegia.
EXAM-CRITICAL: TB requires AIRBORNE precautions — nurses must wear an N95 respirator (not a surgical mask). This is one of the most frequently tested distinctions in GCC nursing exams.
| Feature | N95 Respirator | Surgical Mask |
|---|---|---|
| Filters particles | ≥0.3 μm (95%) | Large droplets only |
| Fit | Tight seal — fit-tested | Loose — gaps present |
| Used for TB by | Healthcare WORKERS | The PATIENT (source control) |
| Transmission type | Airborne precautions | Droplet precautions |
| Required for TB? | YES — mandatory | NO — insufficient |
| Drug | Primary Toxicity | Test / Monitor | Key Exam Point |
|---|---|---|---|
| Rifampicin | Hepatotoxicity, orange secretions, drug interactions | LFTs monthly | Reduces OCP, warfarin, ART efficacy |
| Isoniazid | Peripheral neuropathy, hepatotoxicity | LFTs; give pyridoxine B6 | B6 prevents neuropathy — always co-prescribe |
| Pyrazinamide | Hepatotoxicity, hyperuricaemia, gout | LFTs; uric acid | Most hepatotoxic of the four; causes gout |
| Ethambutol | Optic neuritis (visual acuity + colour vision) | Monthly Snellen + Ishihara test | Stop immediately if any visual change — reversible if early |
DILI rule: AST/ALT >3× ULN with symptoms OR >5× ULN without symptoms = stop H + R + Z. Restart sequentially once LFTs normalise, under senior supervision.
1. Three consecutive negative AFB smears (different days)
2. Clinical improvement documented
3. On effective treatment >2 weeks
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