TB test administration involves:

• A. Injecting the antigen just under the skin
• B. Drawing blood from a vein
• C. Administering an oral vaccine
• D. Injecting the antigen intramuscularly

Answer: (A)

The administration of a tuberculosis (TB) test involves injecting the antigen just under the skin, specifically into the dermal layer. This method is known as the intradermal route. The TB test, such as the Mantoux test, uses a purified protein derivative (PPD) as the antigen. The careful placement of the injection under the skin is crucial because it allows for a localized immune reaction that can be evaluated 48 to 72 hours later.

After the antigen is injected, the body’s immune response to the PPD is assessed by measuring any induration (swelling) at the injection site. This specific intradermal technique is what differentiates the TB test from other testing methods, such as blood tests or vaccines, which do not involve this precise administration or evaluation process.