TB

Question 1

Stain

Answer 1

AFB: Acid-fast bacillus–magenta color
Beaded rods with waxy capsule (mycolic acid, a complex lipid in the cell wall)
Obligate aerobe
Mycobacterium tuberculosis

Question 2

History

Answer 2

Decline in 20th century due to anti-TB drugs

Recent resurgence due to AIDS & drug-resistant strains

Question 3

Prevalence

Answer 3

25K Americans yearly

Most have some sort of lung disease

Question 4

Transmission

Answer 4

Person to person via respiratory aerosols

Question 5

PMNs?

Answer 5

No, no PMNs or purulent lesions
Yes, Granulomas composed of macrophages
Macrophages transform into multi-nucleated giant cells (Macrophages coalesce together)
With caseous necrosis

Question 6

How is it acquired?

Answer 6

1. Primary infection: initial exposure from aerosols by coughing of a person with cavitary TB
2. Organsims multiply in alveoli
3. Alveolar macrophages cannot readily kill

Question 7

Gohn complex (primary TB)

Answer 7

Peripheral parenchymal granuloma
+ Prominent infected draining mediastinal hilar lymph node
In lower lobes

Question 8

Primary infection clinical presentation

Answer 8

1. 90-95% asymptomatic
2. Lesions localized & heal with calcification
   Can be seen with CXR: round dense shadow=coin
   lesion

Question 9

Immunosuppressed/Children with TB

Answer 9

Progressive primary TB
Does not stay limited & heal
Spreads to other parts of children

Question 10

Progressive form of TB

Answer 10

Initial lesion enlarges quickly

Erodes bronchi by necrotic central liquefaction

Question 11

Reactivation/Secondary TB

Answer 11

Dormant lesion reactivates
Bacteria spreads to apex–granulomatous pneumonia
Confluent granulomas cause cavities–hemoptysis
Erodes bronchi & pulmonary blood vessels
ONLY way to spread TB to others

Question 12

Main complication of 2ndary TB

Answer 12

Miliary spread
Multiple, small granulomas in other well-oxygenated organs
GI if swallowed, kidneys, brain
May be disseminated via blood stream erosion

Question 13

Miliary spread complications

Answer 13

Contralateral pneumonia, pleuritis, laryngitis
Scrofula: Lymhphatic spread to hilar nodes + neck infection (Supraclavicular lymph nodes)
Intestinal TB
TB meningitis, around brainstem, optic chiasm, cerebellum.
Pott’s disease: TB osteoarthritis, vertebral column

Question 14

Clinical features

Answer 14

Fever, fatigue, weight loss, night sweats.
95% unrecognized
Secondary TB: Non-productive, dry cough. Fever, loss of appetite, hemoptysis.

Question 15

Miliary spread s/s

Answer 15

1. Scrofula: unilateral cervical adenitis–swollen, nontender nodes
   2.