Tb Testing Flashcards Preview

NHPs > Tb Testing > Flashcards

Flashcards in Tb Testing Deck (13)
Loading flashcards...
1

What is BCG?

Is it effective?

Side-effect?

Bacille-Calmette-Guerin vaccine for TB

It is not 100% effective

Causes false positive reactions to TST

2

What is the test agent for TST?

Storage requirement?

Dose?

Mammalian Old Tuberculin (MOT)

Must be refrigerated until used

0.1mL ID

3

Where is the testing location?

Why this site?

Upper eyelid just above the eyelashes

Easily observed location in unsedated monkeys

 

4

How is the test read?

Read at 24, 48, & 72hr post injection

Eyelid is evaluated for redness, bruising or swelling

Reactions are graded on a scale of 1-5 depending on severity

5

Describe grades 1 through 5 

 

  • Grade 1 -slight bruising of eyelid (negative)
  • Grade 2 -erythema of eyelid without swelling (negative)
  • Grade 3 -varying degrees of erythema with minimal swelling (indeterminant)
  • Grade 4 -obvious swelling with drooping of eyelid (positive)
  • Grade 5 -marked swelling and/or necrosis of eyelid; eyelid closed (positive)

6

Grade?

Interpretation?

Possible Grade 1

NEGATIVE

There is some very mild redness at the test site & no swelling

7

Grade?

Interpretation?

Grade 1

NEGATIVE

Marked bruising associated with the test site, but no swelling

Often due to injection trauma

8

Grade?

Interpretation?

Grade 2

NEGATIVE

Pronounced redness of the eyelid, spread beyond the injection site, NO swelling

9

Grade?

Interpretation?

Grade 3

INDETERMINANT

Slight swelling and drooping of the eyelid +/- erythema

Repeat TST on opposite eyelid

Consider PRIMAGAM or Stat-Pak testing

10

Grade?

Interpretation?

Grade 4

POSITIVE

Marked eyelid droop due to swelling +/- erythema

11

Grade?

Interpretation?

Grade 5

POSITIVE

Eyelid is swollen shut with epiphora present

12

Name 3 reasons for a false-negative TST

  1. Early in disease course or later in advanced dz
  2. Treatment with Isoniazid (Tb Tx drug)
  3. Concurrent immunosuppression (e.g. SIV, Measles)

13

Name three reasons for false-positive TST

  1. Prior exposure to Freunds complete adjuvant
  2. Improper TST administration
  3. Non-specific reation to vehicle in MOT