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Rapid Sputum Tests for Tuberculosis (TB)

British Columbia Specific Information

Tuberculosis, also known as TB, is a serious disease. TB is caused by bacteria that spread through the air when a person with contagious TB coughs, sneezes, sings, or talks. TB usually affects the lungs, but can also affect other parts of the body like glands, bones, joints, kidneys, the brain, and reproductive organs.

For more information on TB, including testing and home isolation, see HealthLinkBC File #51a Tuberculosis (TB), HealthLinkBC File #51b Sputum Testing for Tuberculosis (TB), and HealthLinkBC File #51c Home Isolation for Tuberculosis (TB). For more information about TB, including information about TB clinics and programs, visit BC Centre for Disease Control – Tuberculosis.

Topic Overview

Rapid sputum tests are used to diagnose tuberculosis (TB) when other tests show that a person probably has TB. Rapid sputum tests are also called nucleic acid amplification tests (NAATs).

One of the best ways to diagnose TB is through a sputum culture. A sputum culture is a test to find germs (such as TB bacteria) that can cause an infection. A sample of sputum is added to a substance that promotes the growth of bacteria. If no bacteria grow, the culture is negative. If bacteria grow, the culture is positive. If TB bacteria grow, then the person has tuberculosis. The test also can show if a lung infection is caused by some other kind of bacteria. A sputum culture can take 1 to 8 weeks to provide results.

Rapid sputum tests can tell if a person has TB within 24 hours. A test may be done when:footnote 1

  • A person is thought to have TB, but confirmation is needed before sputum culture results will be ready.
  • A person may be infected with bacteria other than TB bacteria.
  • A person who may have TB has been close to other people who will need treatment if they have been exposed.

References

Citations

  1. U.S. Centers for Disease Control and Prevention (2009). Updated guidelines for the use of nucleic acid amplification tests in the diagnosis of tuberculosis. MMWR, 58(01): 7–10. Available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5801a3.htm?s_cid=mm5801a3_e.

Credits

Current as of:
September 23, 2020

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Brian D. O'Brien MD - Internal Medicine
Adam Husney MD - Family Medicine
W. David Colby IV MSc, MD, FRCPC - Infectious Disease