S8C70 - TB

Question 1

Mycobacterium tuberculosis

Answer 1

• slow growing aerobic rod
• acid-fast cell wall
• settles in areas of high oxygenation
• transmission: droplet nuclei
• 30% of pts will become infected after a significant exposure
• TB can be carried to a lymph node, form a tubercle, caseate, necrotize and calcify to become ghon foci
• mantoux becomes +ve 2mo after exposure`

Question 2

TB: sx

Answer 2

• often asymptomatic
• if active infxn: fever, wt loss, malaise, c/p
• latent that becomes active: night sweats, fatigue, malasie, wt loss, hemopytsis, dyspnea, pleuritic c/p

-20% of cases will have extrapulmonary signs: painless lymphadenopathy, pericarditis, peritonitis, meningitis (acute in children, indolent in adults), adrenal insufficiency, arthritis, pott dz, osteomyelitis, HSM, orchitis, sterile pyuria

Question 3

TB: skin test

Answer 3

• mantoux: delayed type hypersensitivity reaction, occurs in those with past infection, is read at 48-72h, may have false +ve in pts with BCG vaccine as well as those with exposure to non-TB mycobacteria
• false neg occur with improper technique, immunocompromised

Question 4

stain for TB

Answer 4

-aiehl-neelsen

Question 5

TB: Tx

Answer 5

First line agents for 8w (all 4 drugs):
-isoniazid, rifampin, pyrazinamide, ethambutol

Followed by 2 drug continuation tx for 18-31w based on Cx:

• used for drug resistant cases or if SE from 1st line tx aren’t tolerated
• either INH/RIF or INH/rifapentine
• there are other regimens
• 2nd line agents: streptomycin, cycloserine, fluoroquinolones
• to treat latent TB; 9 mo of tx

Question 6

TB: Tx Side effects

Answer 6

• INH: hepatotoxicity

- may worsen with inititiation of tx (paradoxical rxn) or immune reconstitution syndrome (fever, LA, worsening symptoms)

Question 7

Miliary TB

Answer 7

• wide heamtogenous spread during the primary infxn or the secondary seeding of multiple organs in the young of immunocompromised host
• high mortality
• millet seed appearance grossly and distinctive CXR
• cutaneous involvement: papules or vesiculopapules (tuberculosis cutis miliaris disseminata or tuberculosis cutis acuta generalisata), choroidal tubercles on ocular exam (pathognomonic)