The occupational health nurse assesses a health care worker's purified protein derivative (PPD) test and measures 11 mm of induration. The nurse should interpret this finding as
The occupational health nurse assesses a health care worker's purified protein derivative (PPD) test and measures 11 mm of induration. The nurse should interpret this finding as
A. a confirmatory test result for pulmonary tuberculosis.
[25%]
B. a false-negative test result.
[6%]
C. the healthcare worker requires immediate isolation using airborne isolation precautions.
[11%]
D. further testing is required.
[58%]
Statistics
Subject/Lesson
Subject
Fundamentals
Lesson
Safety / Infection Control
Client Need
Test Plan
Health Promotion and Maintenance
Related Topic
Health Screening
Item Type
Item Type
Analysis
Explanation
Choice D is correct. An 11 mm induration after 48 to 72 hours would be recorded as a positive result. However, this does not confirm pulmonary tuberculosis, as further testing (chest x-ray) is required to determine if the client has latent pulmonary tuberculosis. The PPD is not a confirmatory test for pulmonary tuberculosis - a sputum sample is used to confirm an active infection, and a chest x-ray is used for latent infection.
Choice A is incorrect. This test is not a confirmatory test for pulmonary tuberculosis, as a sputum assay is the most accurate test.
Choice B is incorrect. A false-negative result would not be 11 mm. If the test is negative, the induration is less than 5 mm.
Choice C is incorrect. The healthcare worker does not need to be isolated using airborne precautions because the client needs to be assessed further to determine if this result is accurate and if it means a latent or active infection.
Learning Objective
Recognize the cutoff values of positive Mantoux test in those with and without risk factors.
Additional Info
A Mantoux test is also referred to as a purified protein derivative (PPD) test. The PPD is injected intradermally and is read at 48-72 hours. The induration size at 48-72 hours determines whether the PPD is positive or negative. However, the cutoff size of the positive induration diameter is based on specific risk factors. The cutoff sizes depending on the risk factors are as follows:
Induration of 5 mm and more is positive in:
- Immunosuppressed clients (those using long-term steroids, those on immunosuppressive medications)
- Clients who have had recent contact with active TB clients.
- HIV-infected clients
Induration of 10 mm or more is positive in:
- Healthcare workers and residents in high-risk areas (nursing homes, hospitals, prisons)
- Injection drug users
- Children aged less than four years
- Clients who immigrated from countries with high TB prevalence in the last five years.
Induration of 15 mm or more: is a positive test in any person. This includes even healthy clients with no TB risk factors
