Question

A PPD test is administered to a healthy 23 -year-old nurse who is starting employment at a local hospital. Which of the following measurements would be considered a "positive" reading for this individual? a. \(10 \mathrm{~mm}\) of erythema b. \(5 \mathrm{~mm}\) of induration c. \(10 \mathrm{~mm}\) of induration d. \(15 \mathrm{~mm}\) of induration

Short answer

For a healthy 23-year-old nurse, an induration of 10mm or more would be considered positive, thus the correct answer is (c) 10 mm of induration.

Step-by-step solution

Understanding PPD Test Interpretation

The PPD test (Purified Protein Derivative) also known as the Mantoux test, is used to determine if someone has been exposed to the tuberculosis bacterium. The test is read 48 to 72 hours after administration. A positive result is determined by the size of the raised, hard area or induration. The criteria for a positive result vary depending on the individual's risk factors.

Identifying Risk Category for the Individual

In this case, the individual is a healthy 23-year-old nurse who is starting employment at a local hospital. Health care workers are considered to be at a higher risk for TB infection due to their frequent exposure to patients and infectious materials.

Determining the Size Criteria for a Positive Reading in a High-risk Individual

For people in high-risk categories including health care workers like our nurse, an induration of 10mm or more is generally considered positive.

Comparing the Options with the Established Criteria

Given the options a through d, the correct answer would be the one which displays an induration size of 10mm or more, as erythema (redness) is not used to interpret PPD test results.

Key concepts

NCLEX-RN Examination

The National Council Licensure Examination for Registered Nurses (NCLEX-RN) is a standardized test that every nursing graduate must pass to become a licensed registered nurse in the United States. This examination assesses a candidate's knowledge and abilities to perform safely and effectively as an entry-level nurse.

Topics covered on the NCLEX-RN span from the basic understanding of the human body to complex healthcare scenarios including the management of diseases like tuberculosis, which healthcare workers are regularly exposed to. It is essential for nursing candidates to be familiar with interpreting tests like the PPD or Mantoux test, which are used to screen for tuberculosis exposure.

For instance, questions on the NCLEX-RN may present a scenario where nurses are required to interpret a PPD test, just as they would in a real-world healthcare setting. Grasping the concepts behind interpreting these test results is crucial for ensuring public health and safety, and is a typical component of NCLEX-RN preparation.

Mantoux Test

The Mantoux test, also known as the PPD test, is an intradermal injection administered to screen for tuberculosis (TB) infection. The test uses a small amount of a substance called Purified Protein Derivative to elicit an immune response in individuals who may have been exposed to TB.

After the injection, the site is evaluated for a reaction, which is observed as induration (a raised, hardened area) - not to be confused with erythema, which is simply redness of the skin. The size of the induration is measured in millimeters; based on CDC guidelines, different thresholds for what is considered a positive result are established based on the individual's risk factors.

For a general adult population with no risk factors, an induration of 15mm or more is often needed to be considered positive. However, for those with increased risk, such as HIV-positive patients, recent contacts of TB cases, or health care workers, an induration of 10mm or more is suggestive of a TB infection.

Tuberculosis Exposure in Healthcare Workers

Healthcare workers are at an increased risk for exposure to tuberculosis due to the nature of their work environment where they come into contact with patients with active TB and airborne pathogens.

Given this risk, healthcare facilities often implement routine TB screening for their workers as a part of their infection control program. The CDC recommends using the Mantoux test for this purpose and outlines specific criteria for evaluating the test results.

For healthcare workers, a PPD test with an induration of 10mm or more is considered a positive result, indicating a possible TB infection, and leading to additional testing and evaluation. In the case of the nurse in the exercise, with an induration of 10mm or more, further examination and treatment may be needed to ensure patient safety as well as the health and well-being of healthcare personnel.