Question

The Tuberculin skin test _______. Select all that apply.

will be positive if person has had previous exposure
will be positive in active TB
uses a purified protein filtrate of Mycobacterium tuberculosis
involves the injection of PPD intradermally
is caused by gram negative bacteria

Answer 1

The correct statements are:

1. **Will be positive if person has had previous exposure:** True. The Tuberculin skin test (TST) is based on the principle that individuals previously exposed to Mycobacterium tuberculosis will have a delayed-type hypersensitivity reaction.

2. **Will be positive in active TB:** True. A positive TST indicates exposure to the bacteria, but it does not differentiate between latent and active tuberculosis.

3. **Uses a purified protein filtrate of Mycobacterium tuberculosis:** True. The Tuberculin skin test involves injecting purified protein derivative (PPD), which is a protein filtrate derived from Mycobacterium tuberculosis.

4. **Involves the injection of PPD intradermally:** True. The PPD is injected just beneath the skin (intradermally), and the test relies on observing the skin reaction.

5. **Is caused by gram-negative bacteria:** False. Tuberculosis is caused by Mycobacterium tuberculosis, which is a acid-fast, gram-positive bacterium.

Answer 2

The Tuberculin skin test will be positive if the person has had previous exposure to Mycobacterium tuberculosis, in cases of active TB, and uses a purified protein filtrate known as tuberculin. It involves injecting PPD intradermally but is not caused by gram-negative bacteria.

Step-by-step explanation:

The Tuberculin skin test has several characteristics which can be confirmed as follows:

• will be positive if a person has had previous exposure to Mycobacterium tuberculosis, indicative of a cellular immune response to the bacterium
• will be positive in active TB, suggesting that the patient is currently infected with the tuberculosis bacteria
• uses a purified protein filtrate of Mycobacterium tuberculosis, known as tuberculin
• involves the injection of PPD (Purified Protein Derivative) intradermally to check for a delayed hypersensitivity reaction

The statement 'is caused by gram negative bacteria' does not apply to the Tuberculin skin test as it is related to Mycobacterium tuberculosis, which is not a gram-negative bacterium.