Pulmonary Tuberculosis
Model Case Presentation
Patient Demographics
Name: Master Arjun, Age: 5 years, Gender: Male, Informant: Mother (Reliable), Residence: Urban slum, overcrowded household
Chief Complaints
- Low-grade fever — 6 weeks
- Cough — 6 weeks
- Loss of weight and poor appetite — 3 months
History Summary
Mother reports insidious onset of low-grade fever, mostly in evenings, associated with night sweats for the past 6 weeks. Cough is non-productive. The child has lost weight progressively over the past 3 months. He has been lethargic, less playful, and anorexic. No hemoptysis. No breathlessness at rest.
Contact history (key point): The child's paternal grandfather, who lives in the same house, was diagnosed with sputum smear-positive pulmonary TB 2 months ago and is on anti-TB treatment (Category I). He was sleeping in the same room as the child for the preceding 4 months.
BCG scar present on left arm. Immunization up to date. Born at term, NVD. Non-consanguineous marriage. No family history of malignancy or immunodeficiency.
Examination Summary
| Parameter | Finding | Significance |
|---|---|---|
| Weight | 13 kg | Underweight (expected ~18 kg for age); SAM criterion needs check |
| Temperature | 37.9°C (evening) | Low-grade fever |
| RR | 28/min | Normal for age |
| HR | 96/min | Normal |
| SpO2 | 97% on room air | Normal |
| Lymph nodes | Multiple firm, non-tender cervical lymph nodes (largest ~1.5 cm) | Reactive/TB lymphadenitis |
| BCG scar | Present, left deltoid | Vaccinated; Mantoux interpretation adjusted |
Chest examination: Slight dullness and reduced breath sounds in the right upper zone. No crepts, no wheeze. No mediastinal shift.
Other systems: Abdomen — mild hepatosplenomegaly. No clubbing, no edema, no cyanosis. Pallor present (mild).
✅ Complete Diagnosis
Primary Pulmonary Tuberculosis with Ipsilateral Hilar Lymphadenopathy (Primary Complex), in a 5-year-old male with a known household contact of sputum smear-positive pulmonary TB, presenting with classical constitutional symptoms. Mantoux positive (≥10 mm, BCG-vaccinated child). CXR and further evaluation required to confirm.
📝 History — Exam Q&A
Mycobacterium tuberculosis (MTB) — an aerobic, non-motile, non-spore-forming, acid-fast bacillus (AFB). It stains poorly with Gram stain. Detected by Ziehl–Neelsen (ZN) staining (carbol fuchsin, decolorized with acid-alcohol, counterstained with methylene blue) — AFBs appear red on blue background. Doubling time is ~20 hours, making culture slow (2–8 weeks on solid media).
Primarily by inhalation of airborne droplet nuclei (1–5 µm in diameter) from an adult or adolescent with active sputum smear-positive pulmonary TB. Children are rarely the source of infection because they have paucibacillary disease and cannot generate high-velocity cough. The most important risk factor in children is close household contact with an infectious adult.
- Prolonged low-grade fever (>2 weeks), typically evening rise with night sweats
- Persistent cough >2 weeks (often non-productive in children)
- Weight loss / failure to thrive — the most sensitive symptom in children
- Anorexia, lethargy, malaise
- Lymph node swelling (cervical most common)
💡 Pearl
The WHO/IAP screening triad for suspected pediatric TB: Persistent cough >2 weeks + unexplained fever >2 weeks + unexplained weight loss in a child with a known TB contact.
Children rarely harbor enough bacilli to be infectious themselves and always acquire infection from an adult or adolescent source case — usually a household contact. A documented contact with a smear-positive pulmonary TB case is one of the strongest diagnostic clues in children and is a key component of all pediatric TB scoring systems (IAP, Stegen-Toledo).
Additionally, pediatric TB is a sentinel event indicating recent community transmission — identifying the child helps find the adult source, enabling broader infection control.
- No hemoptysis — rules out progressive primary TB with cavity or bronchiectasis (rare in young children)
- No neck stiffness / headache / seizures — rules out TB meningitis
- No joint swelling / back pain / limp — rules out skeletal TB
- No prior TB treatment — excludes relapse or drug-resistant TB
- No steroid use / immunosuppressant — risk of reactivation
- HIV status of family — co-infection alters presentation and management
- BCG vaccination status — affects Mantoux interpretation
- Travel to endemic area — epidemiological risk
After inhalation, MTB reaches the alveoli and is engulfed by macrophages. A localized area of inflammation forms in the lung parenchyma — the Ghon's focus (usually subpleural, middle or lower lobe). Bacilli travel to regional lymph nodes via lymphatics, causing hilar/paratracheal lymphadenopathy. Together, the Ghon's focus + lymphangitis + lymphadenopathy constitute the Ghon's complex (Primary Complex).
- In ~90-95% of immunocompetent children: primary complex heals by fibrosis and calcification → latent TB infection (LTBI)
- In ~5-10%: progression to active disease — risk is highest in infants (<2 yrs) and immunocompromised
| Risk Group | Lifetime Risk of Progression |
|---|---|
| Infants (<1 year) | ~40–50% — highest risk |
| Children 1–2 years | ~25% |
| Children 2–5 years | ~5% |
| Children 5–10 years | ~2% (latent period — "safe school age") |
| Adolescents/Adults | ~5–10% |
| HIV+ children | Much higher — depends on CD4 count |
| Malnourished / SAM | Significantly increased |
By type of disease:
- LTBI (Latent TB Infection): Positive TST/IGRA, no clinical or radiological disease
- Primary TB: Disease resulting from first infection — includes primary complex, progressive primary TB
- Post-primary (Reactivation) TB: Older children/adolescents; upper lobe cavitary disease (adult-type)
By site (pulmonary and extrapulmonary):
- Pulmonary: Primary complex, endobronchial TB, progressive/cavitary
- Extrapulmonary: TB lymphadenitis (most common extrapulmonary), TB meningitis, miliary TB, skeletal, abdominal, pericardial, pleural TB
By bacteriology: Smear-positive, smear-negative, culture-positive, clinically diagnosed (most children fall in this last category)
Used when bacteriological confirmation is unavailable (most children). Points are assigned to key features:
| Feature | Points |
|---|---|
| Symptoms (cough, fever, weight loss >2 weeks each) | 1–3 |
| Close contact with smear-positive TB case | 3 |
| Mantoux ≥10 mm (BCG vaccinated) or ≥5 mm (unvaccinated/immunocompromised) | 3 |
| Chest X-ray suggestive of TB | 3 |
| Malnutrition not responding to 4 weeks of treatment | 1 |
Score ≥7 → Start anti-TB treatment; Score 5–6 → Probable TB, close follow-up; Score <5 → Unlikely TB
Note: The WHO 2022 guidelines now recommend validated clinical decision algorithms incorporating CXR + contact history + symptoms, especially in resource-limited settings.
🩺 Examination — Exam Q&A
General: Low-grade fever, pallor (nutritional anemia), weight loss, muscle wasting. BCG scar on left deltoid. Lymphadenopathy (cervical, axillary).
Chest: Often surprisingly normal in primary TB despite CXR changes. Dullness + decreased breath sounds in areas of lobar consolidation or pleural effusion. Bronchial breathing if consolidation is extensive. Wheeze if endobronchial TB compresses a bronchus.
Abdomen: Hepatosplenomegaly (part of miliary TB or immune activation). Ascites (abdominal TB).
Primary TB in children mainly involves the lymph nodes (hilar) and a small subpleural Ghon's focus, which may not produce enough consolidation or effusion to be detectable on auscultation. The disease is mediastinal and lymph-node-centric, not parenchymal. This is why CXR is critical — it often reveals abnormalities despite a normal chest examination. The hallmark is "more on X-ray than on exam."
- Most common site: Cervical (posterior triangle), followed by axillary, inguinal
- Lymph nodes are firm to rubbery, matted together, initially non-tender
- May become tender as they enlarge and undergo caseation
- "Collar-stud abscess" — necrotic lymph node perforates deep fascia to form a subcutaneous abscess connected by a narrow tract (collar-stud appearance)
- Cold abscess: fluctuant, non-tender, erythematous overlying skin — sign of caseation and liquefaction
- Sinus formation with discharge of caseous material is a late complication
The Ghon's complex (primary complex) consists of:
- Ghon's focus: Small area of consolidation in the lung parenchyma, usually subpleural in the middle or lower lobe
- Lymphangitis: Inflammation along the draining lymphatics
- Hilar/mediastinal lymphadenopathy: Enlarged, caseous regional lymph nodes
On clinical examination, the primary complex is often silent. It is detected on CXR or CT scan. Calcified Ghon's complex (healed) appears as a calcified nodule on X-ray and signifies past infection.
| Complication | Clinical Signs |
|---|---|
| Endobronchial TB / airway compression | Wheeze, stridor, localized air trapping; mediastinal lymph nodes compressing bronchus |
| Segmental collapse-consolidation | Dullness, decreased breath sounds, bronchial breathing — "epituberculosis" |
| Pleural effusion | Stony dullness, absent breath sounds, decreased tactile fremitus |
| Miliary TB | High fever, hepatosplenomegaly, meningism; CXR shows millet-seed pattern |
| TB Meningitis | Neck stiffness, Kernig's sign, Brudzinski's sign, altered sensorium, papilledema |
| TB Pericarditis | Pericardial rub, muffled heart sounds, raised JVP (tamponade) |
A hypersensitivity phenomenon in primary TB where enlarged hilar lymph nodes cause lobar/segmental collapse-consolidation of the adjacent lung by extrinsic bronchial compression. It is not due to direct parenchymal invasion. The affected lobe shows consolidation and collapse on CXR. It typically resolves with anti-TB treatment but may take months. The right middle lobe is most commonly affected (middle lobe syndrome).
- Erythema nodosum: Tender red nodules on shins; hypersensitivity reaction — indicates recent primary TB infection or early active disease
- Phlyctenular conjunctivitis: Small nodules at limbus of cornea; hypersensitivity to tuberculoprotein — highly suggestive of TB in children
- Lupus vulgaris: Reddish-brown plaques/nodules on face; skin TB (rare)
- Scrofuloderma: Skin overlying a tuberculous lymph node breaks down → sinus tract
🔬 Investigations — Exam Q&A
Technique: 0.1 mL of Purified Protein Derivative (PPD) — 5 TU (tuberculin units) is injected intradermally on the volar aspect of the forearm, producing a 6–10 mm wheal (Mantoux technique). Read at 48–72 hours.
Reading: Measure only the induration (not erythema), transversely to the long axis of the forearm, in millimeters.
False positive: BCG vaccination, NTM infection, incorrect technique.
False negative: Immunosuppression (HIV, malnutrition, severe TB itself — "anergy"), recent live virus vaccination (within 3 weeks), very early infection (<8 weeks), miliary TB, TB meningitis.
| Induration | Interpretation | Context |
|---|---|---|
| ≥5 mm | Positive | HIV-positive children; immunosuppressed; recent close contact with confirmed TB; CXR suggestive of prior TB |
| ≥10 mm | Positive | BCG-vaccinated children (standard Indian/WHO cut-off in endemic settings); children <5 years; high-risk groups |
| ≥15 mm | Positive | Low-risk individuals with no exposure history |
💡 Key Point
In India (BCG-vaccinated, high TB burden): ≥10 mm is positive. A strongly positive reaction (≥15 mm with vesiculation, necrosis, or ulceration) indicates high-grade tuberculin sensitivity and is very suggestive of active or recent infection. Mantoux alone does not distinguish LTBI from active disease — it only confirms TB infection.
- Hilar lymphadenopathy — most characteristic; unilateral or bilateral; lobulated hilar shadow ("lobster-claw" appearance)
- Ghon's focus — small homogeneous opacity, usually in mid/lower zone; may calcify later
- Primary complex — Ghon's focus + enlarged hilar lymph nodes ± lymphangitis (dumbbell pattern)
- Mediastinal widening — paratracheal, subcarinal lymphadenopathy
- Segmental collapse-consolidation — due to endobronchial compression (right middle lobe most common)
- Pleural effusion — usually unilateral, exudative
- Miliary pattern — 1–2 mm discrete nodular shadows throughout both lung fields ("snowstorm" appearance)
- Calcified Ghon's complex / Ranke complex — healed primary TB
Children (especially <5 years) cannot expectorate sputum. Accepted specimens include:
- Gastric aspirate (GA) / Gastric lavage (GL): Early morning, child fasting, 3 consecutive days — gold standard specimen in young children. Yields ~30–40% positivity on culture.
- Induced sputum: Nebulize with 3% hypertonic saline → stimulate cough → collect sputum. Yield similar to GA.
- Bronchoalveolar lavage (BAL): Via bronchoscopy; used when above methods fail.
- Stool specimen (NEW — WHO 2022): Non-invasive; children swallow sputum → AFBs pass into stool; 5g sample for Xpert Ultra.
- NPA (nasopharyngeal aspirate): Alternative non-invasive specimen.
- Site-specific: CSF (TBM), pleural fluid (pleuritis), lymph node biopsy/aspirate (TB lymphadenitis)
CBNAAT (Cartridge Based Nucleic Acid Amplification Test) = Xpert MTB/RIF (GeneXpert). It is a rapid, automated, real-time PCR assay that simultaneously detects:
- Mycobacterium tuberculosis DNA
- Rifampicin resistance (as a surrogate for MDR-TB) — detects rpoB gene mutations
Result time: ~2 hours. Recommended as the initial diagnostic test for suspected TB in children (WHO 2022).
Xpert MTB/RIF Ultra: Improved sensitivity over standard Xpert; can detect as few as 16 copies/mL; higher sensitivity in paucibacillary pediatric specimens.
Sensitivity in children: ~60–70% from GA; ~80–90% from BAL. Specificity: >98%.
Culture of Mycobacterium tuberculosis is the gold standard. Culture media:
- Solid media: Löwenstein–Jensen (LJ) medium (egg-based) — results in 4–8 weeks. Colonies appear buff-colored, rough, dry, cauliflower-like.
- Liquid/automated: BACTEC MGIT 960 (Mycobacteria Growth Indicator Tube) — detects growth in 1–3 weeks by oxygen consumption fluorescence. Faster; preferred for drug susceptibility testing (DST).
Culture also allows drug sensitivity testing (DST) — essential for MDR-TB management.
IGRA (Interferon-Gamma Release Assay) is a blood test that measures IFN-γ released by sensitized T-cells when stimulated by MTB-specific antigens (ESAT-6 and CFP-10 — absent from BCG and most NTM).
| Feature | Mantoux (TST) | IGRA (QuantiFERON-TB Gold / T-SPOT.TB) |
|---|---|---|
| BCG effect | False positive due to BCG | Not affected by BCG — more specific |
| Visits | 2 (injection + reading) | 1 (blood draw) |
| Age | Preferred <5 years | Preferred ≥5 years |
| Cost | Cheap, widely available | Expensive, requires lab |
| India/WHO recommendation | Preferred in endemic settings | WHO strongly recommends against IGRA as alternative to Mantoux in India (2019) |
- CBC: Mild normocytic normochromic anemia; raised ESR (non-specific marker of disease activity); lymphocytosis
- ESR: Elevated; useful for monitoring response to treatment
- LFT (liver function tests): Baseline before starting ATT (isoniazid, rifampicin, pyrazinamide are hepatotoxic); monitor if symptomatic
- HIV testing: Mandatory in all children with suspected TB
- Blood sugar: Diabetes is a risk factor
- CT chest: More sensitive than CXR; better delineates mediastinal lymph nodes, cavities, miliary nodules — use if CXR inconclusive or disease extent unclear
- USG abdomen: Abdominal lymphadenopathy, ascites, cold abscess
- Histopathology: Lymph node biopsy — caseating granulomas with Langhans giant cells (pathognomonic)
💊 Management — Exam Q&A
Standard regimen (WHO / RNTCP / India): 2HRZE / 4HR
- Intensive phase (2 months): Isoniazid (H) + Rifampicin (R) + Pyrazinamide (Z) + Ethambutol (E)
- Continuation phase (4 months): Isoniazid (H) + Rifampicin (R)
- Total duration: 6 months
| Drug | Dose (mg/kg/day) | Max dose | Key Side Effect |
|---|---|---|---|
| Isoniazid (H) | 10 mg/kg (range 7–15) | 300 mg | Hepatotoxicity, peripheral neuropathy (give Pyridoxine B6) |
| Rifampicin (R) | 15 mg/kg (range 10–20) | 600 mg | Hepatotoxicity; orange discoloration of urine/secretions; enzyme inducer |
| Pyrazinamide (Z) | 35 mg/kg (range 30–40) | 2000 mg | Hepatotoxicity, hyperuricemia, arthralgia |
| Ethambutol (E) | 20 mg/kg (range 15–25) | 1000 mg | Optic neuritis (color vision and visual acuity loss) — baseline eye check |
💡 WHO 2022 Update — SHINE Trial
For children aged 3 months to 16 years with non-severe drug-susceptible TB (no cavitation, no extensive disease, clinically well), a 4-month regimen (2HRZ(E)/2HR) is now recommended as non-inferior to the standard 6-month regimen. Severe pulmonary TB and extrapulmonary TB still require 6 months.
DOTS = Directly Observed Treatment, Short-course. A strategy endorsed by WHO and implemented under India's NTEP (National Tuberculosis Elimination Programme — formerly RNTCP). Key pillars:
- Political commitment with increased and sustained financing
- Case detection through quality-assured bacteriology (universal drug sensitivity testing — U-DST)
- Standardized treatment with supervision and patient support (daily treatment with DOT)
- An effective drug supply and management system
- Monitoring and evaluation system
Under NTEP India, treatment is daily (not intermittent) and uses fixed-dose combinations (FDCs) in weight-based dosing bands. Treatment is provided free through government health facilities.
TPT prevents progression from LTBI to active TB disease. Indications in children:
- All children <5 years who are household contacts of a smear-positive TB case (regardless of Mantoux result), after ruling out active disease
- Children <5 years who are contacts of any TB case with negative Mantoux — give TPT; retest Mantoux after 8–10 weeks; stop if Mantoux remains negative and child is well
- HIV-positive children with LTBI or who are TB contacts (any age)
- Mantoux-positive children with no evidence of active disease (any age with LTBI)
- Children on immunosuppressive therapy (steroids, biologics)
| Regimen | Details |
|---|---|
| 6H (preferred) | Isoniazid 10 mg/kg/day (max 300 mg) for 6 months |
| 3HR | Isoniazid + Rifampicin for 3 months — alternative |
| 3HP | Isoniazid + Rifapentine weekly for 3 months — ≥2 years; shorter, better compliance |
Corticosteroids are used as adjunctive therapy in specific TB situations to reduce inflammation:
| Indication | Evidence |
|---|---|
| TB Meningitis | Reduces mortality and neurological sequelae — strongest indication; dexamethasone 0.4 mg/kg/day tapered over 4–6 weeks |
| TB Pericarditis | Reduces effusion and constrictive pericarditis risk |
| Endobronchial TB with atelectasis | Prednisolone to reduce airway compression by lymph nodes |
| TB with severe hypersensitivity (erythema nodosum, etc.) | Short course |
| Miliary TB with ARDS or adrenal insufficiency | May be used |
MDR-TB: Resistant to at least isoniazid AND rifampicin (the two most effective first-line drugs). XDR-TB: MDR-TB + resistance to any fluoroquinolone AND at least one second-line injectable agent (bedaquiline/linezolid — updated WHO 2021 definition).
Treatment of MDR-TB in children (WHO 2022):
- Shorter all-oral regimen (6 months): Bedaquiline + Pretomanid + Linezolid (BPaL) — endorsed for children ≥6 years
- Bedaquiline is now approved for children >5 years with MDR-TB
- Delamanid is approved for children ≥3 years
- Avoid injectable agents in children (ototoxicity)
- Treat based on DST results of source case or child's own specimen
Hepatotoxic ATT drugs: Isoniazid (H), Rifampicin (R), Pyrazinamide (Z).
Monitoring:
- Baseline LFT before starting treatment
- Routine monitoring not needed if baseline is normal and patient is asymptomatic
- Monitor if: symptoms of hepatitis (jaundice, RUQ pain, vomiting), severe/disseminated TB, pre-existing liver disease, HIV, severe malnutrition, or high-dose isoniazid
- Stop all potentially hepatotoxic drugs if ALT >5× ULN (asymptomatic) or ALT >3× ULN with symptoms; do not reintroduce until LFT normalizes
- Reintroduce sequentially under monitoring once LFT normalizes
- Miliary TB: Hematogenous dissemination — most deadly; highest risk in infants <2 years
- TB Meningitis: Most feared complication; often follows miliary TB; can cause hydrocephalus, cranial nerve palsies, permanent neurological damage, death
- Pleural effusion → fibrothorax and restrictive lung disease
- Bronchiectasis — from endobronchial disease
- Drug-resistant TB — from inadequate or interrupted treatment
- Skeletal TB (Pott's spine) — vertebral destruction, gibbus deformity, paraplegia
- Constrictive pericarditis
- Growth failure, chronic malnutrition
BCG (Bacille Calmette-Guérin) is a live attenuated vaccine derived from Mycobacterium bovis. Given at birth (or as early as possible) intradermally on the left deltoid.
- Highly protective against: Miliary TB and TB meningitis (80–85% efficacy) — severe forms in young children
- Moderate protection against: TB lymphadenitis, primary pulmonary TB
- Limited protection: Adult-type cavitary pulmonary TB (variable, 0–80%)
- Not a contraindication for Mantoux testing — BCG can cause false-positive Mantoux (usually <15 mm, diminishes with time)
- NOT given to HIV-positive infants — risk of disseminated BCG disease
🔭 Recent Advances — Exam Q&A
SHINE (Shorter Treatment for Minimal Tuberculosis in Children) was a landmark Phase III randomized controlled trial that compared a 4-month regimen (2HRZ[E]/2HR) vs standard 6-month regimen (2HRZ[E]/4HR) in children 3 months to 16 years with non-severe, drug-susceptible TB (pulmonary and peripheral lymphadenitis).
Result: The 4-month regimen was non-inferior to the 6-month regimen with similar efficacy and safety.
Impact: WHO 2022 guidelines now recommend the 4-month regimen as the preferred option for non-severe TB in children aged 3 months–16 years. This improves compliance, reduces drug burden, and lowers cost.
- Enhanced sensitivity: detects as few as 16 copies/mL (standard Xpert: 131 copies/mL)
- Uses 2 additional genetic targets (IS6110 and IS1081) + multicopy elements
- Higher sensitivity in paucibacillary specimens (children, smear-negative, EPTB)
- Can detect trace positivity (very low bacillary load)
- WHO recommends Xpert Ultra as the initial test for pediatric TB (2022)
- Approved for stool specimens in children (non-invasive)
Young children swallow their respiratory secretions (including sputum containing MTB bacilli). These bacilli pass through the GI tract and are excreted in stool. Stool can therefore serve as a non-invasive respiratory specimen for Xpert MTB/RIF Ultra testing.
- WHO 2022 recommendation: Stool strongly recommended for children with presumptive pulmonary TB who cannot produce sputum
- Required amount: 5 g (1 teaspoon)
- Sensitivity ~65–75% for Xpert Ultra from stool
- Avoids invasive procedures like gastric aspirate in young children
- Bedaquiline: Diarylquinoline — inhibits mycobacterial ATP synthase; approved for children ≥5 years (2020); now included in shorter all-oral MDR-TB regimens
- Delamanid: Nitroimidazole — inhibits mycobacterial cell wall synthesis; approved for children ≥3 years (2017); used in MDR-TB when bedaquiline cannot be used
- Pretomanid: Part of BPaL regimen (Bedaquiline + Pretomanid + Linezolid) for XDR-TB and treatment-resistant MDR-TB; increasingly used in older children
- Linezolid: Oxazolidinone — repurposed for MDR/XDR TB; effective but significant side effects (myelosuppression, neuropathy)
WHO 2022 (Module 5) provides two algorithms (A and B) for use in children with presumptive pulmonary TB at healthcare facilities. Both incorporate:
- Symptom screen: Cough, fever, weight loss/poor growth for ≥2 weeks
- TB contact history
- Chest X-ray (Algorithm A) — mandatory if available
- TST/IGRA results
- HIV status
- Bacteriological results (when available)
Weighted scoring leads to a decision to: start treatment / investigate further / observe. This replaces purely clinical gestalt-based decisions and standardizes care in resource-limited settings. The algorithm classifies TB as confirmed, probable, or possible.
TB-IRIS (Immune Reconstitution Inflammatory Syndrome) occurs in HIV-positive children starting ART while already on ATT. As immunity is restored, an exaggerated immune response to residual MTB antigens causes paradoxical worsening of TB symptoms despite effective ATT and ART.
- Onset: Within 4–8 weeks of starting ART
- Features: Fever, enlarging lymph nodes, worsening pulmonary infiltrates, new pleural effusions, CNS manifestations
- Management: NSAIDs for mild cases; corticosteroids (prednisolone 1 mg/kg/day) for severe cases; do NOT stop ATT or ART
- Risk highest when CD4 count is very low at ART initiation
⚡ Key Points — Quick Revision
One-Liners for Exam
- Causative organism: Mycobacterium tuberculosis — acid-fast bacillus (AFB)
- Mode of transmission: Airborne droplet nuclei from adult smear-positive contact
- Primary complex (Ghon's complex): Ghon's focus + lymphangitis + hilar lymphadenopathy
- Highest risk of progression: Infants <1 year (~40–50%) and immunocompromised
- Most common site of extrapulmonary TB: Lymph nodes (cervical most common)
- Mantoux cut-off in BCG-vaccinated children in India: ≥10 mm = positive
- Mantoux cut-off in HIV/immunocompromised: ≥5 mm = positive
- Mantoux does NOT distinguish LTBI from active disease
- Gold standard for diagnosis: Culture of MTB (LJ medium / MGIT 960)
- Fastest diagnosis: CBNAAT / Xpert MTB/RIF Ultra (~2 hours) — also detects rifampicin resistance
- Specimen in young children: Gastric aspirate (3 consecutive early mornings); stool (WHO 2022 — non-invasive)
- CXR in primary TB: Hilar lymphadenopathy + Ghon's focus ± consolidation/collapse
- Miliary TB CXR: 1–2 mm millet-seed nodules throughout both lung fields
- Standard ATT regimen: 2HRZE + 4HR (6 months total)
- SHINE trial: Non-severe TB in 3mo–16yrs → 4 months (2HRZ/2HR) non-inferior to 6 months
- TPT (chemoprophylaxis): Isoniazid 10 mg/kg/day for 6 months — all contacts <5 years or HIV+
- BCG vaccine: Best protection against miliary TB and TB meningitis (80–85%)
- BCG NOT given to: HIV-positive infants (risk of disseminated BCG disease)
- Steroids in TB: Mandatory in TB meningitis (dexamethasone) and TB pericarditis
- Hepatotoxic ATT drugs: H + R + Z; stop all if ALT >5× ULN or symptomatic hepatitis
- MDR-TB: Resistant to H + R; newer drugs: bedaquiline (≥5yr), delamanid (≥3yr)
- TB-IRIS: Paradoxical worsening in HIV+ children starting ART; treat with steroids; do NOT stop ATT/ART
- Collar-stud abscess: Caseous lymph node perforating deep fascia — pathognomonic of TB lymphadenitis
- Epituberculosis: Lobar collapse due to enlarged hilar nodes compressing bronchus — hypersensitivity, not direct invasion
- Phlyctenular conjunctivitis + erythema nodosum: Hypersensitivity manifestations of TB — highly suggestive
- Ethambutol side effect: Optic neuritis → do baseline visual acuity and color vision before starting
- IGRA advantage over Mantoux: Not affected by BCG vaccination — more specific
- NTEP (India): Daily ATT with FDCs in weight-based bands; universal DST; free treatment
🚨 Exam Traps
- A negative Mantoux does NOT rule out active TB — anergy occurs in miliary TB, TBM, severe malnutrition, HIV, immunosuppression
- Children with primary TB often have a normal chest examination despite CXR changes
- The most common cause of death in pediatric TB is TB meningitis
- Rifampicin turns urine orange — warn parents; it's harmless
- Pyridoxine (Vitamin B6) must be co-administered with isoniazid to prevent peripheral neuropathy