Sputum stain for mycobacteria
Sputum stain for mycobacteria is a test to check for a type of bacteria that cause
Acid fast bacilli stain; AFB stain; Tuberculosis smear; TB smear
How the Test is Performed
This test requires a sample of sputum.
- You will be asked to cough deeply and spit any substance that comes up from your lungs (sputum) into a special container.
- You may be asked to breathe in a mist of salty steam. This makes you cough more deeply and produce sputum.
- If you still do not produce enough sputum, you might have a procedure called
- To increase the accuracy, this test is sometimes done 3 times, often 3 days in a row.
The test sample is examined under a microscope. This sputum stain test can give your doctor a quick answer. Another test, called a
How to Prepare for the Test
Drinking fluids the night before the test helps your lungs produce phlegm. It makes the test more accurate if it is done first thing in the morning.
If you are having a bronchoscopy, follow your health care provider's instructions on how to prepare for the procedure.
How the Test will Feel
There is no discomfort, unless a bronchoscopy needs to be performed.
Why the Test is Performed
The test is performed when the doctor suspects tuberculosis or other mycobacterium infection.
Results are normal when no mycobacterial organisms are found.
What Abnormal Results Mean
Abnormal results show that the stain is positive for:
- Mycobacterium tuberculosis
- Mycobacterium avium-intracellular
- Other mycobacteria or acid-fast bacteria
There are no risks with this test, unless bronchoscopy is performed.
Rodino KG, Woods GL, Wengenack NL. Mycobacteria. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 59.
Shete PB, Cattamanchi A, Yoon C. Tuberculosis: clinical manifestations and diagnosis. In: Broaddus VC, Ernst JD, King TE, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 7th ed. Philadelphia, PA: Elsevier; 2022:chap 53.
Review Date: 12/04/2022
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright ©2019 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.
Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Health. Please discuss with your doctor any questions or concerns you may have.