PPD is the standard classification test for identifying Mycobacterium tuberculosis infection and therefore helps diagnose tuberculosis. This test is usually done in people who were in direct contact with patients infected with the bacteria, including current symptoms of the disease, due to the onset of a latent TB infection, which means that the bacteria is installed but has not yet caused the disease. Know the symptoms of tuberculosis.
The PPD test, also known as the Mantoux tubercin test, is performed in clinical testing laboratories using a small injection containing proteins derived from bacteria under the skin, so that it can be evaluated and interpreted preferably by a pulmonologist so that the correct diagnosis can be made. to be made.
- When PPD is positive.
- There is a high chance of being infected with bacteria.
- However.
- The tubercin test alone is not enough to confirm the patient’s exclusion.
- So in case of tuberculosis.
- Your doctor should order other tests such as a chest.
- X-rays or look for bacteria in the sputum.
- For example.
The PPD test is performed in a clinical laboratory by injecting a purified protein derivative (PPD), i. e. purified proteins found on the surface of TB bacteria, proteins are purified so that there is no development of the disease in people who do not possess the bacteria, however, reaction proteins in infected people have been vaccinated.
The support is applied in the foreground, preferably under the skin, then the person can go home and go to the pneumonologist 72 hours after application, at which point the reaction normally appears.
To pass the PPD exam, it is not necessary to provide other special care, it is only recommended to inform the doctor if you are using any type of medication.
This test may be done in children, when the person with the weakened immune system is under embargo, however, it should not be found in people who have the possibility of having a severe allergic reaction.
The results of the PPD problem depend on the size of the skin reaction, as if it were changing in the image and, for this reason, may be:
In some situations, the presence of a larger 5 mm skin reaction does not mean that the person has been infected with the mycobacteria responsible for tuberculosis, as people vaccinated against tuberculosis (BCG vaccine) have an infection with other types of mycobacteria, may have a skin reaction during the test, and are called a false positive result.
Another false negative result, because the person has infection with the bacteria, but there is no reaction in the PPD problem, can occur in cases of people whose immune system is weakened, because it occurs in people with HIV/AIDS, cancer or who use immunosuppressive drugs, in addition to malnutrition, age over 65, dehydration with a serious infection.
Due to the possibility of false results, TB should not be diagnosed solely by the analysis of this test, the pneumonologist should request additional tests to confirm the diagnosis, such as chest x-ray, immunological examinations and sputum smear microscopy, it is a laboratory test in which a patient, usually sputum, is taken and is observed in case of presence of the bacillus responsible for the disease. These tests should also be requested even if PPD is negative, as this test alone cannot be used to rule out diagnosis.