American Board of Internal Medicine (ABIM) Certification Practice Exam

Which of the following indicates that active tuberculosis (TB) is no longer contagious?

1. Adequate tuberculosis treatment for at least 2 weeks

2. Demonstrate improvement of symptoms

3. Have three consecutive negative sputum smears

4. All of the above

The correct answer is: All of the above

The correct answer encompasses all the listed factors, each of which contributes to determining whether a person with active tuberculosis (TB) is no longer considered contagious. Adequate tuberculosis treatment for at least 2 weeks is a critical aspect of TB management. The standard regimen usually involves the administration of multiple antibiotics, and after a minimum of 2 weeks of proper treatment, a significant reduction in the bacterial load in the sputum is expected. This period allows the person to become less infectious as the replication and spread of the bacteria are reduced. Demonstrating an improvement of symptoms is another important indicator. A decrease in symptoms, such as a reduction in cough, fever, and fatigue, suggests a positive response to treatment. While symptom improvement alone does not confirm a lack of contagion, it is a good sign of the body's response to therapy and is typically associated with reduced infectiousness. Having three consecutive negative sputum smears is the gold standard for confirming that an individual is no longer infectious. The sputum smear test detects acid-fast bacilli, the bacterium that causes TB. When three smears taken over time yield negative results, it provides strong evidence that the active disease is being effectively managed, and the risk of transmission to others is significantly minimized.