TB testing Flashcards
PPD stand for …..
purified protein derivative
BCG stands for….
what is BCG vaccine
Bacillus Calmette-Guérin (BCG)
People who received a bacillus Calmette-Guérin (BCG) vaccine against TB may have a false-positive reaction to the PPD test. Some countries outside the United States that have a high prevalence of TB give the BCG vaccine. Many people born outside of the United States have had the BCG vaccine, but it’s not given in the United States due to its questionable effectiveness.
reference: https://www.healthline.com/health/ppd-skin-test
PPD testing - INDURATION of 5mm or more for the group below is positive or negative ?
• HIV-infected persons;
• Recent contacts of persons with infectious TB disease;
• Persons with fibrotic changes on a chest radiograph consistent with prior TB
• Patients with organ transplants (immunosuppressed)
* patients receiving the equivalent of ≥ 15 mg/day of prednisone for ≥ 1 month). (immunosuppressed )
POSITIVE
A small reaction, called an induration, at the site of the test, 5mm or more of firm swelling) is interpreted as positive result in the following groups
• HIV-infected persons;
• Recent contacts of persons with infectious TB disease;
• Persons with fibrotic changes on a chest radiograph consistent with prior TB
• Patients with organ transplants (immunosuppressed)
* patients receiving the equivalent of ≥ 15 mg/day of prednisone for ≥ 1 month). (immunosuppressed )
People who received a bacillus Calmette-Guérin (BCG) vaccine against TB (False Positive)
Members of these high-risk groups may require treatment, but a positive result doesn’t always mean that they have active TB. More tests are necessary to confirm the diagnosis.
Your doctor will follow up on positive results with a chest X-ray, a CT scan, and a sputum test that looks for active TB in the lungs.
reference: https://www.healthline.com/health/ppd-skin-test
FALSE POSITIVE (False-positive reaction to the PPD test) if they had which vaccine… ?
Bacillus Calmette-Guérin (BCG)
People who received a bacillus Calmette-Guérin (BCG) vaccine against TB may have a false-positive reaction to the PPD test. Some countries outside the United States that have a high prevalence of TB give the BCG vaccine. Many people born outside of the United States have had the BCG vaccine, but it’s not given in the United States due to its questionable effectiveness.
reference: https://www.healthline.com/health/ppd-skin-test
PPD testing - INDURATION of 10mm or more for the group of people below is positive or negative ?
Had a negative PPD skin test in the past two years
Have diabetes, kidney failure, or other conditions that increase their TB risk
Healthcare workers
Intravenous drug users
Iimmigrants who’ve come from a country that’s had a high TB rate in the past five years
Under age 4
Infants, children, or adolescents who’ve been exposed to high-risk adults
Live in prisons, nursing homes, and homeless shelters
vaccine against TB (False positive)
POSITIVE Larger reactions (10 mm of swelling or more) are a positive result in people who:
Had a negative PPD skin test in the past two years
Have diabetes, kidney failure, or other conditions that increase their TB risk
Healthcare workers
Intravenous drug users
Iimmigrants who’ve come from a country that’s had a high TB rate in the past five years
Under age 4
Infants, children, or adolescents who’ve been exposed to high-risk adults
Live in prisons, nursing homes, and homeless shelters
vaccine against TB (False positive)
These high-risk groups may require treatment, but a positive result doesn’t always mean that they have active TB. More tests are necessary to confirm the diagnosis.
Your doctor will follow up on positive results with a chest X-ray, a CT scan, and a sputum test that looks for active TB in the lungs.
reference: https://www.healthline.com/health/ppd-skin-test
POSITIVE PPD For people WITHOUT a known risk factor for TB, is an induration of _____ mm or larger firm swelling at the injection site indicates a positive reaction.
15mm
For people without a known risk factor for TB, a 15 mm or larger firm swelling at the injection site indicates a positive reaction.
If these group had PPD skin test LESS THAN 9mm or less are Positive or Negative ?
Had a negative PPD skin test in the past two years
Have diabetes, kidney failure, or other conditions that increase their TB risk
Healthcare workers
Intravenous drug users
Iimmigrants who’ve come from a country that’s had a high TB rate in the past five years
Under age 4
Infants, children, or adolescents who’ve been exposed to high-risk adults
Live in prisons, nursing homes, and homeless shelters
vaccine against TB (False positive)
NEGATIVE
these group of people would be positive with Larger reactions (10 mm of swelling or more) ..
Had a negative PPD skin test in the past two years
Have diabetes, kidney failure, or other conditions that increase their TB risk
Healthcare workers
Intravenous drug users
Iimmigrants who’ve come from a country that’s had a high TB rate in the past five years
Under age 4
Infants, children, or adolescents who’ve been exposed to high-risk adults
Live in prisons, nursing homes, and homeless shelters
vaccine against TB (False positive)
If the patient has induration of 4.5mm at the site of the test. Is this Positive or Negative ?
• HIV-infected persons;
• Recent contacts of persons with infectious TB disease;
• Persons with fibrotic changes on a chest radiograph consistent with prior TB
• Patients with organ transplants (immunosuppressed)
* patients receiving the equivalent of ≥ 15 mg/day of prednisone for ≥ 1 month). (immunosuppressed )
People who received a bacillus Calmette-Guérin (BCG) vaccine against TB (False Positive)
Members of these high-risk groups may require treatment, but a positive result doesn’t always mean that they have active TB. More tests are necessary to confirm the diagnosis.
NEGATIVE 4.5mm or less
this group would be positive with a 5mm or more of firm swelling)
• HIV-infected persons;
• Recent contacts of persons with infectious TB disease;
• Persons with fibrotic changes on a chest radiograph consistent with prior TB
• Patients with organ transplants (immunosuppressed)
* patients receiving the equivalent of ≥ 15 mg/day of prednisone for ≥ 1 month). (immunosuppressed )
People who received a bacillus Calmette-Guérin (BCG) vaccine against TB (False Positive)
Members of these high-risk groups may require treatment, but a positive result doesn’t always mean that they have active TB. More tests are necessary to confirm the diagnosis.
Your doctor will follow up on positive results with a chest X-ray, a CT scan, and a sputum test that looks for active TB in the lungs.
reference: https://www.healthline.com/health/ppd-skin-test
What is An Interferon-Gamma Release Assay (IGRA)
An Interferon-Gamma Release Assay (IGRA)
The tuberculosis (TB) blood test, also called an
Interferon Gamma Release Assay or IGRA, is a way to
find out if you have TB germs in your body. The TB
blood test can be done instead of a TB skin test
(Mantoux).
There are two kinds of TB blood tests:
▪ QuantiFERON®-TB
▪ T-SPOT®.TB
This test (or a skin ppd test) could be ordered to evaluate if the patient has been infected with M. tuberculosis.
