A positive tuberculin skin test indicates infection; what should be done next to determine if it is latent or active TB?

• A. Start treatment immediately
• B. No further testing is needed
• C. Further testing to determine latent vs active
• D. Vaccination against TB

Answer: (C)

A positive tuberculin skin test shows TB infection but doesn’t tell you whether the disease is latent or active. The next step is to gather information and tests that distinguish between the two. Clinically, you’d assess for symptoms such as a persistent cough, fever, night sweats, or unintentional weight loss. Imaging with a chest X-ray helps look for signs of active pulmonary TB, like infiltrates or cavitation. Microbiologic studies are key too: sputum samples tested with acid-fast bacilli smear and culture, often with a rapid nucleic acid amplification test, help confirm active disease and contagiousness. If the evaluation reveals no symptoms, a normal chest X-ray, and negative microbiology, the infection is latent and can be treated accordingly. If symptoms or imaging suggest active TB, you’d start appropriate anti-TB therapy and implement infection control while confirming with culture results.