08.21 - TB (Cross) - Questions Flashcards
TB culture in liquid media will show results in
2 weeks
How does IGRA work
Blood cells from patient are exposed to antigens from MTB and amount of IFN-gamma released from cells is measured
Secondary infection usually involves
Apices of lungs (higher oxygen content)
What protein is thought to play major role in inhibiting phagosome-lysosome function
PknG
What stains tears
Rifampin and related
What is positive PPD if no know risk factors?
>15 mm
What is positive PPD if HIV, recent contact, immunosuppressed?
5-10mm
Only evidence of primary infection in majority of patients is
Calcified lung nodule
Possible NRAMP1 mutation –>
Unchecked bacillary proliferation –> Bacteremia, seeding of multiple sites
How do TH1 cells activate macrophages
IFN-gamma
Why not take rifampin and pyrazinamide together
Liver toxicity
In XDR TB, resistance is to
INH, RIF, Fluoroquinolone, at least one other
Adverse effects of Ethambutol
Optic Neuritis, Vision Discrimination, Hyperuricemia
Function of Sulfatides (Surface Glycolipids)
Inhibit phagolysosome function
Rifampin and other Rifamycins are __ inducers
CYP inducers
Agar used for TB culture
Lowenstein-Jensen Agar
Progressive primary TB initially looks like
Acute bacterial pneumonia: Lobar consolidation, Infiltrates, Adenopathy
What is positive PPD if “at risk”: homeless, nursing home, immigrant, children
10-15 mm
Can’t drink alcohol with
INH
TB remains dormant until
Immune defense are lowered
Spread of strep
Person-to-person (coughing)
Virulent strains grow in characteristic ____ pattern, avirulent strains don’t
cord-like
Most important virulence factor of MTB
Cell wall
Common adverse effect of Ethambutol and Pyraziniamide
Hyperuricemia
___ following primary infection can result in miliary/disseminated TB
Lymphohematogenous Dissemination
Importance of TNF-alpha
TNF-alpha inhibitor will allow granuloma to degrade, freeing and reactivating the TB
Common toxicity of Rifampin and Pyrazinimide
Hepatotoxic
RIPE =
Rifampin, Isoniazid, Pyrazinamide, Ethambutol
__ is produced by TH-1 cells and enables macrophages to contain the infection
IFN-gamma
Inhibits macrophage maturation and induces TNF-alpha release
Cord-Factor
When can PPD be false positive
Immunization with BCG; Infection with nontuberculous MB
What percent of patients who contract TB will contract from smear-negative patients
20%
___ response leads to granuloma formation and caseous necrosis
TH1 response
Rifampin could cause drug-drug interactions in ___ patients
HIV
__ % of patients with primary TB will develop clinically significant disease
5%
Which component of MTB retains AF stain?
Mycolic Acid
Most important determinant of whether over disease occurs
Adequacy of host’s cell-mediated immune response
Anterior leg rash seen in TB
Erythema Nodosum
Cavitation / Bronchial damage more severe in
Immunocompetent patients
TB tx in HIV patients
RIPE for 9-12 months
What cell mediates tuberculin positivity on skin test
TH1
Vision discrimination probs
Ethambutol
Function of Cord Factor
Inhibits macrophage maturation and induces TNF-alpha release
When do we use 4 drug cocktail
Active disease, HIV
Hyperuricemia
Pyrazinamide, Ethambutol
With reduced immune response as in HIV, there are few ___ in sputum
AFB
Hetpatoxic
Rifampin, Pyrazinimide
PPD injection stimulates
Delayed type hypersenstivity by T lymphocytes
In HIV patients with TB, there is incr freq of ___, and absence of ___ in tissues
Incr freq of false negative sputum smears; and absence of granulomas in tissues
How does alveolar macrophage activate T Cell
Class 2 MHC + IL-12
T/F: Mycolic acid cleaves antibiotics to render them ineffective
FALSE
Optic neuritis
Ethambutol
Initial test for TB:
Acid fast; but culture should be done at same time
PPD and IGRA in HIV patients
False negatives in both can occur
In MDR TB, most common resistance is to ___; in ___ patients
INH and RIF; AIDS patients
