TB

Question 1

populations at greatest risk for TB (3)

Answer 1

immunocompromised (HIV)
infants
elderly

Question 2

multi drug resistant (MDR) TB

Answer 2

resistant to isoniazid and rifampin

Question 3

extensively drug resistant (XDR) TB

Answer 3

resistant to INH and rifampin plus any fluoroquinolone and 1+ injectable 2nd line drug

Question 4

virulence mechanism of TB

Answer 4

ability to multiply in macs (CW components disrupt phagosome-lysosome interactions and interfere w/ oxidative killing, TNF alpha secreted --> fever, weight loss, tissue damage)
cord factor (surface glycolipid in virulent strains, trigger Th1 response and enhances survival w/in macs)

Question 5

what is the reservoir for TB?

Answer 5

cavitary lung lesions filled w/ m. tb

–particles must be 1-5u to reach alveoli where they can cause infection

Question 6

what drug is typically used for chemoprophylaxis for TB? (for latent)

Answer 6

isoniazid for 9 months

alternative: rifampin for 4 months, isoniazid-rifapentenet once weekly for 12 weeks

Question 7

risks for MDR TB

Answer 7

prior tx (poor adherence, poor supervision)
foreign born
HIV
cavitary TB
exposure to MDR-TB

Question 8

where does reactivated disease usually occur?

Answer 8

upper, well oxygenated lobes of lung

*post apical segment of upper lobes and upper segments of lower lobes

Question 9

BCG vaccine

Answer 9

live, attenuated vaccine derived from m. bovis
greatest protection against disseminated TB seen in infants and young children
doesn’t help prevent infection but induces a more rapid response by alveolar macrophages –> prevents bacteremia
contraindicated in preg, HIV/immunocompromised