A nurse has been exposed to tuberculosis (TB) during care of a patient with TB and has a TB skin test performed. When is the nurse considered infected?
There is no redness or induration at the injection site.
There is an induration of only 5 mm at the injection site.
A negative skin test is followed by a negative chest x-ray.
Testing causes a 10-mm red, indurated area at the injection site.
The Correct Answer is D
A nurse is considered infected with tuberculosis (TB) when the tuberculin skin test (TST) reveals an induration of 10 mm or greater at the injection site, indicating prior exposure to Mycobacterium tuberculosis. The reaction reflects an immune response to TB antigens injected under the skin, signifying latent or active infection. Because health care workers are at increased occupational risk, this threshold is used to determine infection and guide further evaluation, including a chest x-ray and confirmatory testing.
Rationale for correct answer:
4. Testing causes a 10-mm red, indurated area at the injection site.
An induration (raised, firm area—not redness) of 10 mm or more is considered positive in individuals such as health care workers, recent immigrants, or those with frequent exposure to TB. This indicates infection with Mycobacterium tuberculosis and the need for further evaluation, including a chest x-ray and possible interferon-gamma release assay (IGRA).
Rationale for incorrect answers:
1. There is no redness or induration at the injection site.
A lack of induration means the test is negative, indicating no infection or no immune response.
2. There is an induration of only 5 mm at the injection site.
An induration of 5 mm is considered positive only in high-risk groups (e.g., HIV-positive individuals, recent TB contacts, or immunosuppressed patients). For healthy nurses, 10 mm is the diagnostic threshold.
3. A negative skin test is followed by a negative chest x-ray.
A negative result on both tests suggests no infection, but does not meet the criteria for being “infected.”
Take-home points:
- Induration, not redness, determines TST results.
- ≥10 mm is considered positive for health care workers.
- A positive TST requires follow-up with a chest x-ray and possible TB blood test.
- Annual TB screening helps protect healthcare personnel and patients.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
The nurse should interpret bronchial breath sounds in the lower lung fields as an abnormal finding. Normally, bronchial sounds are heard only over the trachea and mainstem bronchi. When these harsh, high-pitched sounds are heard in the peripheral lung areas, it indicates that lung tissue has become consolidated or filled with fluid, as seen in conditions such as pneumonia.
Rationale for correct answer:
4. Bronchial breath sounds in the lower lung fields. These sounds are characterized by a loud, tubular quality with a longer expiratory phase. In healthy lungs, the alveoli dampen bronchial sounds, so they should not be heard in the lower fields. Their presence there suggests abnormal air-to-fluid or air-to-solid ratios, typically caused by lung consolidation, atelectasis, or fibrosis. This finding warrants prompt investigation to identify the underlying pathology.
Rationale for incorrect answers:
1. Inspiratory chest expansion of 1 in. Normal chest expansion during inspiration is about 1 inch (2.5 cm) and should be symmetric. This finding is expected and indicates adequate lung inflation.
2. Percussion resonance over the lung bases. Resonance is the normal percussion tone over healthy lung tissue, reflecting air-filled alveoli. It indicates normal lung aeration and is not abnormal.
3. Symmetric chest expansion and contraction. Equal movement of both sides of the chest during breathing reflects normal respiratory mechanics and adequate bilateral lung expansion.
Take-home points:
- Bronchial breath sounds heard in peripheral or lower lung fields are a key sign of abnormal lung consolidation or fluid accumulation.
- Normal findings include resonant percussion tones and symmetric chest expansion.
- Recognizing changes in breath sound location or quality is essential for early detection of respiratory pathology.
- Document abnormal findings clearly and notify the provider for further evaluation, such as imaging or sputum testing.
Correct Answer is ["A","B","E"]
Explanation
Age-related changes that lead to decreased secretion clearance include decreased functional cilia, decreased force of cough, and decreased functional immunoglobulin A (IgA). These physiological changes impair the respiratory system’s ability to remove mucus and trapped pathogens, increasing the risk of airway obstruction and infection in older adults.
Rationale for correct answers:
1. Decreased functional cilia. With aging, the number and activity of cilia decline, reducing mucociliary clearance. This makes it harder for mucus and debris to move upward and out of the airways, predisposing older adults to respiratory infections.
2. Decreased force of cough. Age-related weakening of respiratory muscles and reduced chest wall elasticity decrease cough strength, limiting the ability to clear secretions effectively. This contributes to mucus retention and airway compromise.
5. Decreased functional immunoglobulin A (IgA). IgA helps defend against pathogens on mucosal surfaces. A decline in IgA levels and effectiveness weakens immune protection, allowing microorganisms to proliferate in retained secretions.
Rationale for incorrect answers:
3. Decreased chest wall compliance. Although reduced compliance affects breathing mechanics and expansion, it does not directly influence the body’s ability to clear secretions.
4. Small airway closure earlier in expiration. This contributes to air trapping and reduced ventilation efficiency, but it does not directly cause decreased secretion clearance.
Take-home points:
- Aging decreases cilia activity, cough strength, and IgA function, impairing secretion clearance.
- Impaired clearance increases the risk of infection, mucus retention, and atelectasis.
- Encourage hydration, pulmonary hygiene, deep breathing, and coughing exercises to promote secretion removal.
- Preventive care such as vaccinations and respiratory monitoring helps reduce complications in older adults.
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