TB Test Core Knowledge and Fundamentals 2 — Questions and Answers
Question 1: Which bacterium causes tuberculosis?
- Mycobacterium tuberculosis (Correct answer)
- Streptococcus pneumoniae
- Staphylococcus aureus
- Klebsiella pneumoniae
Correct answer: Mycobacterium tuberculosis
Tuberculosis is caused by Mycobacterium tuberculosis, a slow-growing aerobic bacterium.
Question 2: A two-step TST is recommended for which population?
- Adults who will be tested repeatedly, such as healthcare workers (Correct answer)
- Children under age 5
- Immunocompromised patients only
- People who have never been vaccinated with BCG
Correct answer: Adults who will be tested repeatedly, such as healthcare workers
Two-step testing is used for people who will be retested periodically, like healthcare workers, to establish a baseline and distinguish boosting from new infection.
Question 3: What is the primary route of Mycobacterium tuberculosis transmission?
- Airborne droplet nuclei (Correct answer)
- Direct skin contact
- Contaminated food or water
- Blood transfusion
Correct answer: Airborne droplet nuclei
TB spreads via airborne droplet nuclei (<5 microns) that are expelled when an infectious person coughs, sneezes, or speaks.
Question 4: In the United States, which federal agency publishes TB testing guidelines for healthcare settings?
- CDC (Correct answer)
- OSHA
- FDA
- CMS
Correct answer: CDC
The Centers for Disease Control and Prevention (CDC) issues TB testing and prevention guidelines for healthcare and other settings.
Question 5: Which of the following best describes latent TB infection (LTBI)?
- TB bacteria are present but not causing active disease or symptoms (Correct answer)
- Active disease limited to one lung lobe
- Infection that is resistant to isoniazid
- TB confined to lymph nodes only
Correct answer: TB bacteria are present but not causing active disease or symptoms
In LTBI, the immune system contains the bacteria so the person has no symptoms and is not infectious, but bacteria remain alive.
Question 6: Which chest X-ray finding is classically associated with post-primary (reactivation) TB?
- Upper lobe infiltrates or cavitation (Correct answer)
- Bilateral lower lobe consolidation
- Pleural effusion only
- Mediastinal widening
Correct answer: Upper lobe infiltrates or cavitation
Reactivation TB characteristically involves the upper lobes and apical segments, often with cavitation.
Question 7: PPD stands for what in the context of TB skin testing?
- Purified Protein Derivative (Correct answer)
- Positive Pulmonary Detector
- Primary Prevention Dose
- Protein-Polysaccharide Derivative
Correct answer: Purified Protein Derivative
PPD (Purified Protein Derivative) is the antigen preparation injected intradermally during the Mantoux tuberculin skin test.
TB Test Core Knowledge and Fundamentals 2
Which bacterium causes tuberculosis?