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Tuberculosis

NCLEX Review Guide: Pediatric Tuberculosis

Pathophysiology and Etiology

Causative Agent

  • Tuberculosis (TB) in children is caused by Mycobacterium tuberculosis, an acid-fast bacillus that primarily affects the lungs but can disseminate to other organs. The bacterium is transmitted through airborne droplets when an infected person coughs, sneezes, or speaks.

Key Points

  • Children most often contract TB from close, prolonged contact with infected adults, typically household members.
  • Infants and young children are at higher risk for progression to active disease after infection compared to adults.

Disease Progression

  • Pediatric TB follows a two-stage process: primary infection followed by either containment or progression to active disease. After inhalation, the bacteria establish in the lungs forming the Ghon focus (primary lesion) and may spread to regional lymph nodes creating the Ghon complex.

Key Points

  • Children have a higher risk of extrapulmonary TB and disseminated disease (miliary TB and TB meningitis).
  • The incubation period from infection to positive tuberculin skin test is 2-10 weeks.

Risk Factors

  • Several factors increase a child's susceptibility to TB infection and progression to active disease, including age (younger than 5 years), immunocompromised status, malnutrition, and recent TB exposure.

Key Points

  • Children under 5 years and adolescents have the highest risk of progression to active TB after infection.
  • HIV co-infection significantly increases the risk of TB disease and mortality.

Clinical Manifestations

Signs and Symptoms

  • Pediatric TB often presents with non-specific symptoms, making diagnosis challenging. Common symptoms include persistent cough (>2 weeks), low-grade fever, night sweats, weight loss or failure to thrive, decreased activity, and fatigue.

Key Points

  • Children may be asymptomatic even with significant disease.
  • Infants often present with more acute and severe symptoms than older children.

Extrapulmonary Manifestations

  • Children have a higher incidence of extrapulmonary TB compared to adults. Common sites include lymph nodes (scrofula), central nervous system (TB meningitis), bones/joints, and disseminated disease (miliary TB).

Key Points

  • TB meningitis presents with headache, irritability, vomiting, and altered consciousness and has high mortality if not treated promptly.
  • Lymph node TB (cervical lymphadenitis) is the most common form of extrapulmonary TB in children.

Clinical Scenario

A 4-year-old boy presents with a 3-week history of low-grade fever, persistent cough, decreased appetite, and weight loss. His grandmother was recently diagnosed with pulmonary TB. Physical examination reveals cervical lymphadenopathy and decreased breath sounds in the right upper lobe. This presentation is highly suspicious for pulmonary TB with possible lymph node involvement.

Diagnosis

Tuberculin Skin Test (TST)

  • The Mantoux tuberculin skin test involves intradermal injection of purified protein derivative (PPD) and measurement of induration (not erythema) after 48-72 hours. Interpretation is based on the size of induration and risk factors.

Key Points

  • ≥5mm induration is positive in high-risk children (HIV-infected, recent TB contacts, immunosuppressed).
  • ≥10mm induration is positive in children <4 years old or with other risk factors.
  • ≥15mm is positive in children ≥4 years with no risk factors.

Interferon-Gamma Release Assays (IGRAs)

  • IGRAs (QuantiFERON-TB Gold and T-SPOT.TB) are blood tests that measure the immune response to TB antigens. These tests are less affected by previous BCG vaccination than TST.

Key Points

  • IGRAs are preferred for BCG-vaccinated children >2 years of age.
  • Both TST and IGRA can be negative in immunocompromised children and infants <2 months.

Microbiologic and Radiographic Studies

  • Diagnostic confirmation requires isolation of M. tuberculosis from clinical specimens. Chest radiographs may show hilar lymphadenopathy, lobar infiltrates, cavitation (rare in young children), or miliary pattern.

Key Points

  • Children often have paucibacillary disease, making bacteriologic confirmation more difficult than in adults.
  • Gastric aspirates, induced sputum, or bronchoalveolar lavage may be needed to obtain specimens.

Comparison: TST vs. IGRA

Feature Tuberculin Skin Test (TST) Interferon-Gamma Release Assay (IGRA)
Administration Intradermal injection Blood test
Follow-up Requires return visit in 48-72 hours Single visit
BCG interference May cause false-positive results Not affected by BCG vaccination
Age limitation Can be used at any age Limited data in children <2 years
Cost Lower Higher

Treatment

Latent TB Infection (LTBI)

  • Treatment of LTBI aims to prevent progression to active disease. The standard regimen is isoniazid (INH) for 9 months, though shorter alternative regimens may be used in select cases.

Key Points

  • All children <5 years with recent TB exposure should receive window prophylaxis even if initial TST/IGRA is negative.
  • Alternative regimens include: 4 months of rifampin or 3 months of once-weekly isoniazid plus rifapentine (for children ≥2 years).

Active TB Disease

  • Treatment for active TB requires a multidrug regimen to prevent resistance. The standard initial phase consists of isoniazid, rifampin, pyrazinamide, and ethambutol for 2 months, followed by isoniazid and rifampin for 4 months (continuation phase).

Key Points

  • Directly observed therapy (DOT) is recommended to ensure adherence.
  • Treatment duration is extended for certain forms of extrapulmonary TB (e.g., 9-12 months for TB meningitis and bone/joint TB).

Medication Side Effects and Monitoring

  • Anti-TB medications can cause significant adverse effects. Regular monitoring includes clinical assessment, liver function tests, and vision screening for children on ethambutol.

Key Points

  • Isoniazid can cause hepatotoxicity and peripheral neuropathy (prevented with pyridoxine/vitamin B6 supplementation).
  • Rifampin causes orange discoloration of body fluids and can interfere with hormonal contraceptives.

Important Alert

Children on isoniazid should be monitored for signs of hepatotoxicity (jaundice, abdominal pain, nausea, vomiting). Medications should be immediately discontinued if ALT/AST exceeds 3 times normal with symptoms or 5 times normal without symptoms.

    Steps for Administering and Reading a Tuberculin Skin Test

  1. Cleanse the volar surface of the forearm with alcohol and allow to dry.
  2. Using a 27-gauge needle, inject 0.1 mL of PPD intradermally, creating a 6-10 mm wheal.
  3. Mark the site with a pen or have the patient/parent mark it.
  4. Instruct the patient to return in 48-72 hours for reading.
  5. Read the test by measuring the induration (hardened area) perpendicular to the long axis of the forearm.
  6. Document the measurement in millimeters, not simply as "positive" or "negative."

Nursing Management

Assessment

  • The nurse should perform a comprehensive assessment, including TB exposure history, presence of symptoms, nutritional status, and growth parameters. Document baseline vital signs, respiratory assessment, and weight for medication dosing and monitoring treatment response.

Key Points

  • Assess all household contacts and identify the potential source case.
  • Document BCG vaccination history, which may affect test interpretation but not treatment decisions.

Patient and Family Education

  • Comprehensive education is essential for treatment adherence and successful outcomes. Nurses should provide information about the disease, transmission, treatment regimen, potential side effects, and importance of completing the full course of therapy.

Key Points

  • Use age-appropriate language and visual aids to explain concepts to children.
  • Emphasize that most children with TB are no longer infectious after 2 weeks of effective therapy.

Infection Control

  • Children with TB are rarely infectious because they typically have paucibacillary disease, produce weak coughs, and have fewer cavitary lesions. However, adolescents with adult-type cavitary disease can be infectious.

Key Points

  • Hospitalized children with suspected or confirmed pulmonary TB should be placed in airborne isolation until determined non-infectious.
  • Children with TB generally do not need to be excluded from school once treatment is initiated and adherence is established.

Memory Aid: First-Line TB Drugs - "RIPE"

  • R - Rifampin (turns body fluids orange)
  • I - Isoniazid (requires vitamin B6/pyridoxine)
  • P - Pyrazinamide (can cause hepatotoxicity)
  • E - Ethambutol (monitor visual acuity and color discrimination)

Prevention

BCG Vaccination

  • The Bacillus Calmette-Guérin (BCG) vaccine contains live attenuated Mycobacterium bovis. It is used in many countries with high TB prevalence but is not routinely administered in the United States.

Key Points

  • BCG provides moderate protection against severe forms of TB in children (meningitis and miliary TB).
  • BCG vaccination can cause false-positive TST results but does not affect IGRA results.

Contact Investigation

  • When a TB case is identified, all household and close contacts should be evaluated, with priority given to children <5 years and immunocompromised individuals. This includes symptom screening, TST/IGRA testing, and chest radiographs for those with positive tests or symptoms.

Key Points

  • Children <5 years with negative initial testing should receive window prophylaxis until repeat testing 8-12 weeks after exposure.
  • Finding a child with TB should prompt investigation for an adult source case.

Summary of Key Points

  • Etiology and Risk: Pediatric TB is caused by Mycobacterium tuberculosis and is usually contracted from close contact with infected adults. Children <5 years and adolescents have the highest risk of progression to active disease.
  • Clinical Presentation: Children often present with non-specific symptoms including persistent cough, fever, weight loss, and fatigue. They have higher rates of extrapulmonary TB compared to adults.
  • Diagnosis: Diagnosis involves TST or IGRA testing, chest radiography, and microbiologic confirmation when possible. Children often have paucibacillary disease, making bacterial confirmation challenging.
  • Treatment: LTBI is treated with isoniazid for 9 months or alternative shorter regimens. Active TB requires multidrug therapy for at least 6 months, with longer durations for certain extrapulmonary forms.
  • Nursing Care: Nursing management includes comprehensive assessment, medication administration and monitoring, patient/family education, and coordination of care to ensure adherence to the treatment plan.

Commonly Confused Points

Latent TB Infection vs. Active TB Disease

Feature Latent TB Infection (LTBI) Active TB Disease
Symptoms No symptoms Symptomatic (cough, fever, weight loss)
Infectiousness Not infectious Potentially infectious (pulmonary/laryngeal TB)
Chest X-ray Normal or shows healed granuloma Abnormal (infiltrates, cavities, adenopathy)
Bacteriology Negative cultures Positive cultures or molecular tests possible
Treatment Single drug (usually INH) Multiple drugs (usually 4 initially)
Treatment duration 3-9 months (regimen dependent) 6+ months (site dependent)

Pulmonary vs. Extrapulmonary TB in Children

Feature Pulmonary TB Extrapulmonary TB
Primary site Lungs Lymph nodes, CNS, bones/joints, etc.
Common findings Hilar lymphadenopathy, infiltrates Site-specific (e.g., lymphadenopathy, meningeal signs)
Diagnosis CXR, sputum/gastric aspirates Site-specific imaging and sampling
Treatment duration Usually 6 months Often extended (9-12+ months for CNS/bone)
Infectiousness Possible (especially in adolescents) Rarely infectious

Common Pitfalls in Pediatric TB Management

  • Failing to consider TB in children with non-specific symptoms, especially with known TB exposure
  • Interpreting TST based on "positive/negative" rather than millimeters of induration and risk factors
  • Not providing window prophylaxis to young children with recent TB exposure regardless of initial test results
  • Inadequate monitoring for medication side effects, especially hepatotoxicity
  • Prematurely discontinuing isolation for potentially infectious cases

Study Tips

Memory Aid: TB Risk Factors in Children - "ABCDE"

  • Age (<5 years or adolescent)
  • BCG unvaccinated
  • Close contact with infectious TB case
  • Deficient immunity (HIV, malnutrition)
  • Endemic area residence or travel

Memory Aid: Extrapulmonary TB Sites - "MENTAL"

  • Meningeal (CNS)
  • Enteric (gastrointestinal)
  • Nodes (lymphatic)
  • Thoracic (pleural, pericardial)
  • Articular (bones and joints)
  • Liver/spleen (miliary spread)

Quick Check: Test Your Knowledge

  1. A 3-year-old with a household TB contact has a negative initial TST. What is the appropriate next step?
    Answer

    Initiate window prophylaxis with isoniazid and repeat TST in 8-12 weeks.

  2. What is the most common form of extrapulmonary TB in children?
    Answer

    Lymph node TB (cervical lymphadenitis/scrofula)

  3. What medication should be given with isoniazid to prevent peripheral neuropathy?
    Answer

    Pyridoxine (Vitamin B6)

  4. What is the standard treatment duration for uncomplicated pulmonary TB in children?
    Answer

    6 months (2 months intensive phase with 4 drugs, followed by 4 months continuation phase with 2 drugs)

Self-Assessment Checklist









Remember, children with TB often present differently than adults. Keep TB in your differential diagnosis for children with non-specific symptoms, especially with known TB exposure. Your knowledge of pediatric TB can make a critical difference in early diagnosis and successful treatment outcomes!

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