Mantoux test or tuberculin skin test (TST) is an examination carried out to determine the presence or absence of germs causes of tuberculosison the body. This test is highly recommended for those of you who often have direct contact with people with tuberculosis.
Tuberculosis (TB) is a lung disease caused by bacteria Mycobacterium tuberculosis which can be contagious. Transmission of TB disease can occur through the air, for example when a TB patient coughs and then splashes his saliva containing the bacteria inhaled by people around him.
Mantoux Test Procedure
The Mantoux test is done by injecting a small amount of a liquid called a PPD tuberculin, on the skin of the arm. After the injection, usually a small lump will form on the surface of the skin.
The doctor will mark the initial boundary around the lump using a marker so that it can be seen if there is a change in the size of the lump. 48-72 hours after the Mantoux test is done, the doctor will re-examine the lump that has formed to see any changes.
If there is no enlargement of the lump, it can be concluded that the Mantoux test result is negative or the patient has not been exposed to TB germs. Meanwhile, the test results that show an increase in the size of the lump, usually as much as 5-9 mm and visible inflammation, this means that the Mantoux test is said to be positive, i.e. the patient is currently or has been exposed to TB germs. The results of this test require further examination to determine whether TB infection is present.
Things That Can Affect Mantoux Test Results
Although it can be used as a reference to determine the presence or absence of TB germs in the body, the results of the Mantoux test can be wrong in certain conditions. This is known as a false negative or false positive test result.
In a false negative test result, the Mantoux test will show a negative result, when in fact the patient is infected with TB germs. Incorrect results of this test can be caused by several things, such as:
- The inability of the body to react to skin tests due to a weak immune system.
- New TB infection occurs, which is between 8-10 months
- TB infection has been around for a long time (years)
- New to vaccines containing live viruses, such as measles or smallpox vaccines.
- Have an illness caused by a virus, such as measles or chickenpox.
- Suffering from a disease that lowers the immune system, such as cancer or AIDS.
- Incorrect injection technique
- Misinterpreting the reaction that appears
Meanwhile, for a false positive test result, the Mantoux test will show a positive result, even though the patient is not actually exposed to TB germs. Incorrect test results can be caused by several things, such as:
- Identified the presence of bacteria Mycobacterium, but not the type tuberculosis
- New to BCG immunization
- Incorrect injection technique
- Using the wrong antigen bottle
- Misinterpreting the reaction that appears
Although the Mantoux test can be a measure of the presence of TB germs in the body, there are often errors in the results of this test. Therefore, for more accurate results, doctors will usually recommend further examinations, such as chest X-rays and sputum examination, to determine whether or not there is a TB infection in the body.