What is the purpose of the tuberculin skin test?

The purpose of the tuberculin skin test, also known as the Mantoux test, is to determine if someone has been exposed to the bacteria that causes tuberculosis (TB). This test involves injecting a small amount of tuberculin purified protein derivative (PPD) into the skin and observing the reaction after 48 to 72 hours. A positive reaction indicates that the person's immune system has responded to the tuberculin, suggesting they have been exposed to TB bacteria at some point, though it does not confirm active TB disease.

This screening method is crucial in public health to identify individuals who might need further testing, such as a chest X-ray, to determine whether they have latent TB infection or active TB disease. Recognizing exposure is an important step in controlling and preventing the spread of TB, particularly in populations at higher risk.

In contrast, diagnosing active TB requires more comprehensive tests, such as sputum analysis or imaging studies. Assessing treatment effectiveness pertains to monitoring the response to therapy in individuals already diagnosed with TB. Checking for antibiotic resistance involves laboratory testing of bacterial samples to see if they can survive treatment with specific antibiotics, which is a separate and advanced diagnostic process.