TB

Question 1

What is the pathogenesis of a TB infection?

Answer 1

1. inhaled bacilli are ingested by macrophages

2. bacilli replicate within macrophage, kill it, and spread hematogenously upon release

Question 2

How is a TB infection contained by a normal immune system?

Answer 2

via cell-mediated macrophage and lymphocyte response; granulomas develop in involved tissues and wall off persistent mycobacterium

Question 3

Reactivation TB occurs if:

Answer 3

immunity wanes in future (after granuloma formation) due to HIV, infection, steroids, immunosuppressants, cancer, etc

Question 4

Persons likely to have been infected recently:

“external”

Answer 4

• close contact
• tuberculin conversion within 2 yrs
• new immigrants from areas of high TB prev
• residents/employees of prisons, NH, etc
• exposed health care workers
• HIV (+)
• IV drug users
• kids exposed to high-risk adults

Question 5

Who should be screened for TB?

Answer 5

Persons likely to have been infected recently

Persons in conditions that increase risk of progression from latent to disease state

Question 6

Medical Conditions of High Risk for TB

Answer 6

• Diabetes mellitus
• Silicosis (*destroys macroph)
• Prolonged corticosteriod therapy
• Other immunosuppressive therapy
• Cancer of the head and neck
• Lymphomas and Leukemias
• Organ transplant recepient
• End-stage renal disease
• Intestinal bypass or gastrectomy
• Chronic malabsorption syndromes
• Low body weight: >10% below the ideal

Question 7

Pulmonary TB symptoms

Answer 7

cough
fever
night sweats
weight loss
hemoptysis

Question 8

Pulmonary signs of TB

Answer 8

Cachexia
Signs of consolidation
Rales: crackles
Advanced: respiratory failure

Question 9

Extra-pulm signs of TB

Answer 9

Renal- pyurea
Meningeal- fever, neck stiffness, coma
Bony- Potts Disease, neuropathies
Scrofula- cervical lymphadenitis (WTF did I misspell?)

(EXTRa PuLM = extremities (bony/neuropathy), pyurea, lymphadenitis, meningitis)

Question 10

In (+) IGRA test, T cells of individuals infected with MTB produce ____ when exposed to…

Answer 10

interferon-gamma

the MTB antigen

Question 11

What is a strength of IGRA testing?

Answer 11

more sensitive than TST
more specific than TST
do not have to return to clinic to get results

Question 12

What tests can be used for detecting latent tuberculosis infection?

Answer 12

TST or the interferon-gamma release assay

Question 13

In USA, most reported cases of TB have:

Answer 13

abnormal chest radiograph

Question 14

What 2 signs are more common in primary TB?

Answer 14

Adenopathy and pleural effusion

Question 15

What is more common in reactivation TB?

Answer 15

Apical disease and cavities

Question 16

What can be seen with both reactivation and primary TB? What does this signify?

Answer 16

Miliary TB

ICH

Question 17

The gold standard of TB diagnosis:

Answer 17

culture-isolation of MTB with sputum (preferably spontaneously expectorated)

Question 18

The five commandments of diagnosis of

Tuberculosis:

Answer 18

Suspect the disease from demographics
Culture appropriate specimens 
Obtain Chest X-ray
PPD skin test 
Examine (symptoms and signs)

=SCOPE

Question 19

1st line TB drugs (6)

Answer 19

1. Isoniazide
2. Rifampin
3. Pyrazinamide
4. Ethambutol
5. Rifabutin
6. Rifapentine

(“RIPE”)

Question 20

2nd line TB drugs

Answer 20

1. Amikacin
2. Kanamycin
3. Capreomycin
4. Ethionamide
5. Fluoroquinolones

Question 21

Patients are no longer considered infectious

if…

Answer 21

On adequate therapy with multiple agents.

Had a significant clinical response to therapy.

Had 3 consecutive negative sputum smears.

Question 22

After TB exposure, ____% will have a positive skin test. Of these, ___% will actually develop disease, but only if…

Answer 22

25%
10%
immunosuppressed

Question 23

During the first ___ years after infection, people are at a high risk of developing TB.

Answer 23

2

Question 24

The containment of TB in the body is the function of:

Answer 24

macrophages and lymphocytes

Question 25

When does tuberculin conversion occur? When will a skin test be (+)?

Answer 25

6-10 weeks after infection | 2 weeks after exposure

Question 26

Where will TB likely spread in the body?

Answer 26

bone brain lungs kidneys

Question 27

The incidence of TB in the US is (increasing/decreasing)

Answer 27

decreasing

Question 28

The current goal of TB screening is to identify:

Answer 28

those at high risk of developing TB from a latent infection

Question 29

What is the greatest known risk factor for reactivation of latent TB?

Answer 29

HIV | 10% risk per year of developing TB if hx of (+) skin test; 40% co-infection rate in inner city clinics

Question 30

Symptoms of pulmonary tuberculosis are:

Answer 30

nonspecific pulmonary systemic

Question 31

Preventive therapy for TB is mainly targeted to...

Answer 31

secondary prevention (infected but latent)

Question 32

Acceptable regimens for latent TB infections (3):

Answer 32

INH daily or twice weekly x9mo INH daily or twice weekly x6mo Rifampin daily x4mo

Question 33

T/F: If a drug is failing in TB trx, add another abx.

Answer 33

F! bad for resistance

Question 34

Regiments for active TB infections:

Answer 34

PZA or EB x2mo INH or RM x6mo (is this right? I was confused)