Approach to detecting TB in youth - CPS Statement Flashcards
What are the BCG contraindications?
BCG is contraindicated for infants with a family history of immunodeficiency or who are suspected of being immunodeficient
What is the difference between a Ghon focus and Ghon complex?
The parenchymal site of infection with Mtb bacilli is a Ghon focus.
Ghon complex includes adjacent hilar lymphadenopathy.
What percent of cases in children exposed to TB develop clinical disease?
5-10%
Re-activation of latent TB disease occurs most often after what age?
10 years
The majority of children exposed to TB who develop primary symptoms do so within ____ after exposure.
1 year
What are the CXR findings for active TB?
Radiographs typically show focal pneumonitis or subtle ‘ground glass’ opacities, with (usually) hilar, mediastinal or subcarinal lymphadenopathy
In TB meningitis, what does the CSF cell count typically show?
Cerebrospinal fluid (CSF) typically shows pleocytosis, with lymphocytic predominance.
What are the risk factors for re-activation of latent TB in children?
Aside from likely host genetic factors, other risk factors include:
1) Immunosuppression (e.g., human immunodeficiency virus (HIV) infection or diabetes)
2) Malnutrition
3) Medications (especially steroids or biologics)
In children who can’t produce sputum, how can you diagnose TB?
In children who cannot expectorate sputum, fasting gastric aspirates obtained on three consecutive mornings are useful for culture
All patients with TB disease require serology for ____.
HIV
A positive TST is a Type ___ hypersensitivity reaction.
Type IV
What are the cut-offs for a positive TST in those who are immunocompromised or a close contact? What is the cut-off for everyone else?
≥5 mm induration for individuals who are immunocompromised and contacts of cases
≥10 mm for others
How do the IGRA tests work?
Interferon-gamma release assays:
In-vitro blood tests that evaluate immune response by measuring the release of interferon-gamma by T-cells in response to antigens specific for Mtb
No cross-reactivity with BCG
How do TST skin tests work?
Tuberculin is a purified protein derivative (PPD) from heat-inactivated Mtb.
When injected intradermally as a tuberculin skin test (TST), a type IV hypersensitivity reaction (wheal) occurs if the recipient has been infected with Mtb or if they have cross-reactive antigens from non-tuberculous mycobacteria (NTM) or from BCG vaccine
Which test is more specific: TST or IGRA?
Specificity is >95% for an IGRA, compared with 60% for a TST
Will an IGRA/TST be positive in latent disease?
Typically yes
In children ≥2 years old, which test is more specific - IGRA or TST?
TST and IGRA were thought to have similar sensitivity and specificity for diagnosis of LTBI
In children <2 years old, which test is likely more sensitive for TB?
TST is possibly more sensitive than IGRA.
Since this group is at higher risk for disease progression, the more sensitive TST is currently recommended over IGRA
What are the initial steps when you have a patient identified as a contact of a positive TB person? (Hint: 4 steps)
1) Conducting a history and physical exam
2) Requesting chest radiographs
3) Performing an initial TST
4) Obtaining the index case’s drug sensitivities is also required
Child contacts <5 years of age with a close contact and an initial TST of <5 mm should receive ____
Preventive prophylaxis (also known as ‘window prophylaxis’, with one TB drug), using a drug that has been identified as effective for treating the source case strain
Child contacts <5 years of age with an initial TST of <5 mm require a repeat TB test at what interval?
Second TST at 8-10 weeks after last contact with infectious case
A child ≥5 years old with a close contact and an initial TST <5 mm in size requires ____
Needs a BOC TST 8 to 10 weeks later, although window prophylaxis is not recommended in this age group.
When can you discontinue window prophylaxis in a child <5 years with a close contact and TST <5 mm?
Child contacts <5 years old, with a BOC TST <5 mm in size at 8 to 10 weeks, can then have window prophylaxis discontinued
Child contacts ≥5 years who have no symptoms and whose physical exam and chest radiographs appear normal, with an initial or BOC TST of ≥5 mm, should receive ____
Treatment for latent infection
