Tuberculin is a purified protein derivative (PPD)which is a protein extracted from Mycobacterium tuberculosis – the bacteria responsible for causing tuberculosis in humans. It is used in a dermatological test to find out is a particular individual has been exposed to tuberculosis.The product based segment of the tuberculin sales market is characterized into Old tuberculin (OT) and Purified Protein Derivative (PPD).The preparation of tuberculin in most widely used today is purified protein derivative (PPD) tuberculin.PPD is either done via multiple-punctures or injected into the skin. If there is any reaction at or in the surrounding area of site of injection, the test is positive.Tuberculin test is conducted by intradermal injection is also termed as the Mantoux test. The test is done to determine if an individual has been exposed to tuberculin protein, either from environmental exposure to this bacterium, or from an earlier tuberculosis vaccination. In other words, the test is done by inserting a little amount of TB protein (antigens) beneath the topmost layer of skin on the patient’s inner forearm.
As per observation, if the patient has ever been exhibited to Mycobacterium tuberculosis, the patient’s skin will respond to the antigens by creating a tough red bump at the injection site within two days.This test is often done when screening, symptoms, or testing such as chest x-rays, indicate that a person might have tuberculosis. However, tuberculin does not have the potential to determine whether how long a person has been infected with TB, and if the infection is active or inactive or if it can be contagious.A few common side effects of tuberculin are itchiness, redness and pain at injection site. Also, in some rare cases, allergic reactions might occur.The tuberculin test might indicate a false positive result in people who have earlier been infected by any other kind of mycobacteria or vaccinated with BCG. It is made out of an extract of Mycobacterium tuberculosis.
Why is tuberculin done?
A tuberculin test is done to determine if people who have tuberculosis, and the following:
- Individuals in close proximity to people suffering from TB
- Medical care workers who probably are exposed to TB
- Individuals with TB symptoms like night sweats, cough, and sudden weight loss
- Abnormality in chest X-ray
- Patients with recent history of organ transplant
- People with compromised immune system, HIV/AIDS
People who have the following must not take the tuberculin test:
- Already existing tuberculosis
- Who have had extreme reaction to TB antigens in the past
- Have an existing skin rash that makes determining the skin test difficult
Disclaimer: The information given in this write-up is purely for educating the reader. It is not meant to be a substitute for any advice from a medical expert.