Final answer:
The tuberculin skin test results are checked 48 to 72 hours after the test administration, looking for redness, swelling, or hardness as indicators of exposure to TB bacteria.
Step-by-step explanation:
The tuberculin skin test results are typically read within 48 to 72 hours post-administration. During the test, tuberculin, a protein extract of the TB bacteria, is introduced into the skin. After the specified time, healthcare professionals look for signs of a delayed hypersensitivity reaction, which include observable swelling, redness, or hardness at the injection site, known as induration.
A positive result indicates that the person has been exposed to Mycobacterium tuberculosis and has a cellular immune response to it. However, False positives may occur in individuals previously vaccinated with the BCG vaccine. Further diagnostic methods, such as chest radiographs, may be needed to confirm TB exposure.