TB 1

Question 1

what organism causes tuberculosis

Answer 1

mycobacterium tuberculosis

Question 2

what is meant by latent TB disease

Answer 2

infected but asymptomatic; disease is not active

Question 3

what makes something considered multidrug resistant TB

Answer 3

TB resistant to at least 2 preferred anti-TB drugs

Question 4

what countries are at high risk for TB

Answer 4

mexico 
philipines
Vietnam 
india 
china

Question 5

what age is most commonly affected by TB

Answer 5

25-44

Question 6

what are the risk factors for TB

Answer 6

1. age: 25-44
2. low SES
3. non-caucasion
4. prolonged contact with infected
5. HIV (most important risk factor)

Question 7

what are the caracteristics of mycobacterium tuberculosis?

Answer 7

gram positive aerobic with unusual waxy coating

Question 8

what immune system response is essential to controlling M. tuberculosis infections

Answer 8

T-lymphocytes

Question 9

what are the primary T cells involved in immune response to TB

Answer 9

CD4+ (a type of T-lymphocyte)

Question 10

what are the 3 factors that contribute to TB disease progression

Answer 10

1. amount of M. TB organisms inhaled
2. virulence of the organisms
3. host’s cell-mediated immune response

Question 11

if someone has latent disease, will they test positive on skin test? how long can they remain latent

Answer 11

yes, will test positive

may be latent for the rest of there lives

Question 12

how does active infection occur from a latent infection

Answer 12

immune system fails to wall off infection during the primary infection

Question 13

when is the highest risk of going from latent to active

Answer 13

2 years after infection

Question 14

what are the 4 screening guidelines for TB screening

Answer 14

1. emigration within 5 years from high prevalence countries
2. Immunosuppressed patients
3. close contacts of people with active TB
4. those with evidence of recent TB infection

Question 15

what are 4 downfalls of PPD skin test

Answer 15

1. booster effect
2. prior BCG vaccination can mess up results
3. requires multiple visits to conduct test
4. subjective interpretation

Question 16

PPD measures presence of cellular immunity by assessing what

Answer 16

delayed-type hypersensitivity

Question 17

what blood test can be done for TB

Answer 17

quantiferon gold (gold standard)
T-SPOT

Question 18

what do blood tests for TB look for

Answer 18

interferon-gamma release

Question 19

what are 4 advantages to blood tests for TB over skin tests

Answer 19

1. provides quick and specific results
2. no booster effect
3. prior BCG does not effect results
4. lab based assay - unbiased interpretation