Mycobacterium Tuberculosis

Question 1

TB Staining

Answer 1

Acid fast: Takes up carbolfuschsin stain

Due to high concentration of mycolic acids in cell wall

Requires Lowenstein Jensen medium to grow and takes weeks to grow

Question 2

Virulence factors that are similar to Nocardia

Answer 2

Acid fast

Obligate aerobe

Question 3

Spreading

Answer 3

Via respiratory secretions

But then stays and grows in host macrophages

Question 4

Cord factor

Answer 4

Protects the bacteria from being destroyed- increases TNF alpha— allows bacteria to be walled off within a set of Mphages

Question 5

Sulfatides

Answer 5

Prevent phagolysosomal fusion; to prevent destruction of TB by preventing exposure to lysosomal hydrolases

Question 6

Virulence factors

Answer 6

Acid-fast, cord factor, sulfatides, and residence in host Mphages

Question 7

Progression of TB

Answer 7

Progression of primary TB

1. Healed latent infection
2. Systemic infection (miliary TB)
3. Reactivation TB

Question 8

Primary infection

Answer 8

generally infects lower and middle lobes

forms Ghon complexes- fibrotic calcifications of lung parenchyma (3 lobes-left, 2 lobes-right); these can infiltrate hillier lymph nodes

Question 9

Granulomas

Answer 9

Collection of activated macrophages (langerhan giant cells)

Forms caseating granulomas (necrotic Mphages, tubercles)

Question 10

Symptoms- primary

Answer 10

Primary symptoms: prolonged fever; most often in children

Most often, resolves by fibrosis, and becomes latent

Develop + PPD- due to Type IV hypersensitivity reaction

Question 11

+ PPD

Answer 11

Active or latent infection
BCG vaccine (attenuated Mycobacterium bovis, but low effectiveness)

Question 12

Systemic infection

Answer 12

Bacteremia
Can affect bone, liver, and lymphatics (miliary TB- lethal)
Variable presentation based on the organ affected
Keep on differential when someone acutely decompensates, and is from an endemic area

Question 13

Reactivation of latent infection

Answer 13

Uncommon (5-10% of ppl)
Associated with immunosuppression- due to down regulation/ inhibition of TNF-alpha release
S&S: Cough, hemoptysis, night sweats; upper lobe infection, cachexia

Question 14

Infliximab/ immunosupression

Answer 14

First screen for presence of TB with PPD

Question 15

Reactivated TB

Answer 15

S&S: Cough, night sweats, hemoptysis

Cachexia: because of TNF-alpha production secondary to release of cord factor

Question 16

Skeletal effects

Answer 16

Pott’s syndrome: TB infection in vertebral bodies (bones)

Question 17

CNS effects

Answer 17

Meningitis, tuberculoma- cavitary lesion in brain

Question 18

Treatment of TB

Answer 18

Often resistant to multiple drugs
R- Rifampin
I- Isoniazid
P- Pyrazinamide
E- Ethambutol

Question 19

Prophylaxis to TB

Answer 19

Rifampin and Isoniazid (9 mo)