Questions: An induration of 18 mm is noted in response to the Mantoux test. What is the likely conclusion? Active tuberculosis Quarantine needed Negative Mantoux result Chest x-ray follow-up

The answer is the fourth one: Chest x-ray follow-up.

Explanation for each option:

1. Active tuberculosis: An induration of 18 mm in the Mantoux test indicates a positive result, suggesting TB exposure or infection, but it does not confirm active tuberculosis. Further tests, such as a chest x-ray, are needed to determine if the disease is active.

2. Quarantine needed: Quarantine is not immediately required based solely on a positive Mantoux test. Additional assessments, including a chest x-ray and possibly sputum tests, are necessary to determine if the person is contagious and requires isolation.

3. Negative Mantoux result: An induration of 18 mm is considered a positive result, not negative. The size of induration considered positive can vary based on risk factors and patient history, but 18 mm is generally positive for all groups.

4. Chest x-ray follow-up: This is the appropriate next step after a positive Mantoux test to check for active tuberculosis. A chest x-ray can help determine if there are any signs of active TB in the lungs.

In summary, a chest x-ray follow-up is the likely conclusion after noting an 18 mm induration in response to the Mantoux test.