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Flashcards in TB Deck (46)
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31

Why is such long treatment regimen needed for TB?

-granuloma blocks ABX
-organism is slow growing

32

What is MDR TB?

resistant to INH and RIF (common in AIDs patients)

33

What is XDR TB?

resistance to INH, RIF, fluoroquinolone, and at least 1 other drug

34

How does HIV affect TB?

-increased frequency of false negative sputum smears
-absence of granulomas
-cavitation/bronchial damage less severe

35

How is latent Tb diagnosed?

-PPD (purified protein derivative)
-IGRA

36

How does a PPD work?

I.D. injection of tuberculin material which stimulates a delayed type hypersensitivity mediated by T cells (causes induration within 48-72 hrs)

37

What can cause a false positive PPD?

immunization with BCG or infection is a non-TB mycobacteria

38

How does an IGRA (Quantiferon gold Quan-TB, T-spot) work?

Patient blood cells are exposed to antigens from MTB and the amount of INF-y released is measured. (no false positive from BCG or NTM infections)

39

Latent Tb tests in HIV patients

False negatives can occur in both tests due to lack of immune response, called anergy

40

How is latent Tb treated?

INH for 9 months OR

INH and Rifapentine for 3 months

41

What determines a positive PPD?

risk factors

42

What is a positive PPD in someone with no known risk factors?

15+mm

43

What is a positive PPD in a homeless, IVDU, nursing home resident, recent immigrant, children under 4?

10-15mm

44

What is a positive PPD in a HIV, immunosuppressed, organ transplant, prior TB?

5-10mm

45

Do you measure the erythema or induration in a PPD?

induration!

46

How can TB be prevented?

-screen those with risk factors
-treat latent converters
-masks